SharpSky ASCOM compliant digital focuser project

[dtrewren]

Hello fellow imagers,

I thought I would share my focuser project with fellow imagers from 'down under'. I have had quite a bit of interest in the the project from Australia and have already send a few kits south of the equator.

The project is an ASCOM compliant digital focuser and comprises of the following key components :

- ASCOM compliant software driver tested with many popular client packages such as MaximDL, ImagesPlus, APT .....

- Control box based around a powerful PIC micro controller and custom PCB

- Stepper motor with reduction gearbox

- Aluminium beam coupler to couple motor & scope focuser

- Manual motor control with user variable rate

- Temperature compensation

The best way to see what the project is all about is to check out the website : www.dt-space.co.uk/SharpSky_Kit

Hope you like the project, will be very interested to hear what you think :)

Cheers & clear skies,

Dave (Bristol UK)

[wasyoungonce]

Hi folks.

I've been following this stepper motor system development for some time now, even built the original unit (http://www.dt-space.co.uk/SharpSky/) based on an ebay development card.

Dave add temperature compensation (http://www.dt-space.co.uk/SharpSky_TC/) to this and refined the firmware/software (http://dt-space.co.uk/SharpSkyClient/).

I liked the unit so much (as did others) Dave had dedicated PCBs made and put it out in kit form which I snapped up for myself and another IIS user. Dave did a fine job with the PCB kit, just neat...the little things, like:
Routing the PCB Temp probe tracks to the a dedicated sensor jack and also thru the motor DB9 connector (so you can put the temp sensor near the focuser);
Routed the PCB motor DB9 connector so it was the same as Moonlite/Robofocus pin to pin compatiable and also routed these tracks to a header (if you want a different connector).

I don't often get excited about things and it would have to be special for me to do so...as big Kev used to say (for those old enough) "I'm excited"!

I'm running the SharpSky with a new Moonlite clutched motor system...works a treat. Good thing about the ML...you can change your geared stepper for ~$90USD for more/less step positional accuracy.

The best thing about this stepper controller...works with all ASCOM compliant focus software!

Future developments...well that's up to Dave to tell suffice to say.....there is more in the skunk works.:thumbsup:

[dtrewren]

Hi Brendan,

Many thanks for the very positive feedback :) very much appreciated. I have really enjoyed this project and that fact that lots of others have built focusers and are using them in the field makes it all the more satisfying.

For me buying new gear is always really nice but building something to do the job always makes me smile whenever I use it :)

Any imagers from 'down under' that are interested or have questions please drop me a message.

Cheers & clear skies,

Dave

[wasyoungonce]

Here are some pics of David's SharpSky controller up and running a ML stepper.:thumbsup:

One of the neat thing about this system is not only the automatic but the manual control. It serves three proposes:
Manual in/out stepping by rotating;
Change number of manual in/out steps each knob movement makes, by depressing knob and rotating then re-depressing knob; and
Firmware update..depress knob when applying power.

[allan gould]

I had a look at this site and was extremely impressed - it really looks excellent.

[wasyoungonce]

I got 2 controller kits from Dave, one for David and myself...but alas I butchered my case trying to drill large holes for the temp and manual control connectors. I didn't as yet have a step drill, I now do:sadeyes:!

Thanks to the design, cheap replacements available for $6 from element14. Crisis over.:lol:

[mswhin63]

Hi Brendan,

How do you go with products like APT or other software in driving the focuser. I use APT and it has focus controlling function in it and interested in operating it as one package. I also use EQMOD.

[wasyoungonce]

Just tried APT ver 1.71 (it's a little old) but focuser ran fine, no problems connecting and stepping. I have been mucking around for ages getting ML stepper, building etc ...just got it all running, no scope time yet...apart from bench runs.

I read EQASCOM pad works fine...somewhere in the UKAIO projects forum (http://ukastroimaging.co.uk/forums/index.php?board=26.0).

edit:
yep foundthe post (http://ukastroimaging.co.uk/forums/index.php?topic=53135.msg448776#msg 448776), Dave the developer tried it all out with EQASCOM pad ok.

Just tried APT ver 1.93...runs sharpsky focuser sweet.

[mswhin63]

Cool thanks Brendon, looks like a great project. Moving house at the moment so not enough resources to purchase anything as yet but will do. Couldn't be bothered building my own system for now.

[dtrewren]

Hi Brendan et al,

Excellent, like the images - really cool to see the kit up and running, looks like you have done a fine job. All we all need now is some fine weather to get outside and do some imaging. Saying that the UK short nights are now here so the mount has been brought inside for a tune and some tlc.

If anyone has any questions or suggestions regarding the SharpSky focuser please drop me a message. Suggestions are always welcome so things can be improved.

Cheers & clear skies,

Dave

[Poita]

Nice, I haven't had time to build mine yet!

[wasyoungonce]

Malcom, and all...Dave has released a new driver for SharpSky focuser, which fixes a direction of movement issue with some programs like APT.

With the new driver, SharpSky direction can be reversed in the properties dialogue. Some programs, like APT, the direction of movement "in/out" was not the same direction SharpSky focuser would move. In focus control programs like FOCUSMAX this was not an issue as they have reverse direction movement control.

I tried APT with ShaprSky...worked fine..but I didn't notice the direction of travel...this attends to this issue.

New driver available here (http://www.iceinspace.com.au/forum/www.dt-space.co.uk/SharpSky/source/SharpSky%20Setup.exe).

[dtrewren]

Hello fellow imagers,

I have had a request or two for some close up images of the SharpSky board to give a better idea of what is involved when building a kit. As can be seen the board is relatively simple, no surface mounted parts or anything like that. The larger IC is the PIC microprocessor and the smaller IC is the Darlington motor driver.

Hope that helps :)

Cheers & clear skies,

Dave

[garymck]

Hi all,

just received my kit from Dave. I expected to get a box full of components, and to have to sort them out. Instead I got a box full of components, each in a seperate little plastic bag, with a printed identifying label on it and neatly packed. This alone will probably save me a heap of time in the build. Dave has also been outstanding in email support. Looking forward to getting it working. Took 7 days to get here in Melbourne.

cheers
Gary

[wasyoungonce]

Hi Gary...what ever you do ....use a step drill for the mini DIN holes....

I butchered my case trying to drill & file these:ashamed:. Anyway, element14 has same cases cheaply...I obtained a new one but with a flange lid as this suits me better for mounting.

Good things come from bad.....errrr that's what I tell myself!:whistle:

Brendan

[dtrewren]

I totally second that suggestion !

For drilling holes into plastic (like ABS) or other soft materials the step drill is invaluable.

For anyone not familiar with the tool here is a photo :

Clear skies,

Dave

[mswhin63]

I agree, I use stepped drills lots of time and well worth it. I also got my last lot from bunnings as well, although I still have my original one form nearly 10 years ago and is still going strong.

[wasyoungonce]

Finally finished my new case. This one has a flange lid which will make it easier to mount. Next to it is a std non-flange case.

[peter_4059]

Dave,

If I'm reading your site correctly it looks like the kit contains the stepper motor and coupling but not the mounting bracket. Is it possible to post some images of the stepper motor, coupling and how it attaches to existing focusers?

Peter

[dtrewren]

Hi Peter,

Yes you are correct. The only component not included is the mounting bracket . I couldn't really get into fabricating brackets as obviously there are many scopes fitted with many different models of focuser so trying to create a range of mounting brackets would have been tricky to say the least. I have fitted the SharpSky focuser to both my Skywatcher ED80, ED120 and my custom widefield rig.

The 'original' web-site based around using a prototype board rather than a PCB
http://www.dt-space.co.uk/SharpSky/

has several videos showing the motor, bracket and fitting onto a SW ED80. The nice thing about using the flexible aluminium coupler is that it soaks up any small errors in the bracket fabrication. The motor has to be lined up reasonably well but if there is a small misalignment the coupler prevents the motor from damaging itself or the focuser mechanics.

If you want more detail please let me know :)

clear skies,

Dave

[wasyoungonce]

Dave and users, a few observations on the controller kit. These are some points I have experienced and are not necessarily criticisms but more things to watch for. In any case constructive criticisms are good...brings about constructive change and I know you are a pro-active person generally more than one-step ahead!:

1. The power PCB jack is 2.1mm centre +ve. I stick to 2.5mm centre ....mixing sizes can be a real pain in the field...especially if you fit a 2.5 centre plug in a 2.1 jack...you get intermittent power drop-outs. It's not an issue using 2.1mm however if you want 2.5mm they can easily/cheaply be changed prior to install....it's just users should be aware of this. We all have out favourite sizes and we all differ.:D

2. The PCB DC jack is recessed in the case (as are all connectors apart from the the motor DB9) so you need to bore a wide enough hole so the the power plug fits thru the case to the jack. The PCB power jack is designed for a 10mm shaft connectors...but...you can get these connectors in 14mm shafts! Thus if you use a longer 14mm power plug shaft (see here (http://www.jaycar.com.au/productView.asp?ID=PP0512)and here (http://www.jaycar.com.au/productView.asp?ID=PP0515)) you do not need to bore the power jack hole so wide...just to fit thru the case!;)

3. I found you need to bore the temp and hand controller mini DIN holes in the case larger than mentioned. I found the case walls are at a slight angle and to allow straight plug entry you may need 13~14mm holes.

4. I found the supplied LED clips distorted when the LED's were fitted, I had some Jaycar 3mm LED clips that worked better. I also needed to bore the clip holes larger than the 4mm.

5. I have had issues with the fly LED PCB holes. I damaged a few fly leads when testing (broke off the fly leads) un-soldering the left overs was a real pain and I damaged one via, obviously my fault! :mad2: I couldn't solder wick (with flux) out the remaining solder so I had to bore the holes with a .6mm drill and this damaged the hole via feed thru. This is not a design fault just clumsy hands.....but..in light of that I would really like a header and plug system for these LEDs instead of the current system. Yes I know the constraints of size and height (for the case design) but maybe a small header/plug (not the std 2.54 size SIL) ...I've seen on fleabay....somewhere?

6. Mounting....obviously as with most DIY mounting is a thing you work out yourself. I have designed stuff and had the same attitude. However, I found the flanged lid version of the case allows itself to mounting better than the original case, see above pics. If you want to replace the case then element 14 has cheap flanged lid cases (here (http://au.element14.com/hammond/1591xxasflbk/box-abs-flanged-100x51x25mm/dp/1511192?Ntt=1591XXASFLBK)).

The above is not a name a shame it's just things I experienced in building the controller that others may come across. Oh, I'm anal when doing things like this (due to my background) so what I say may be frivolous to many!

Might I say..."Damn this system works well".......keep up the good work Dave, I'm a devoted fan and you know we speak similar language.;)

[dtrewren]

Hi Brendan et al,

That's cool I like the feedback because as you say it allows things to be updated for the better. Here is some feedback on your points :

1. Good point regarding the 2.1mm power sockets. I actually have a pile of 2.5mm sockets here so if anyone fancies swapping over I can supply the larger pin centre part.

2. Interesting on the power plug length .... I'll check the one I am using because have not had a problem with the plug clicking into place.

3. I'll update the document to reflect a larger hole diameter. I suspect if the drill wanders a touch when drilling a slightly larger hole maybe required to get the DIN plug to line up with the socket ..... mechanics always the tricky part.

4. I'll see if I can get some slightly longer clips designed for deeper plastic.

5. The current PCB V1.1 has slightly larger holes for the LED & motor breakout and the kit is supplied with five pin molex headers. So you solder in the headers and plug the motor directly into the PCB to test. Once tested you can cut the lead from the motor and use this lead + plug to wire up the LED's. See attached photo of the motor plugged in for test.

6. Yep mounting is down to personal preference - I bought some magnetic sticky plastic strip and fitted this to the mount and focuser case. The focuser controller just sticks to the side of the mount.

More feedback the better I say :)

Very pleased all is working well .... i'll get into looking at the issues ASAP !

Cheers & clear skies,

Dave

[wasyoungonce]

Hi Dave

Thanks for the feedback. re: your attached image......"them's the connectors I was looking for"! They are slightly lower than the std polarised SIL!

As usual Dave.....your always one or two steps ahead!;)

As for a flanged case....I was thinking it would easy to just use some sticky pad under the case and wrap zip ties around the OTA so they hold on to the flange lids..simple...well for me but of course this may not suit others.

:hi:Brendan

[dtrewren]

Hi Brendan,

I was a bit upset about the headers on the first revision of the board. I had intended headers to be used in order to make build and test easier. Unfortunately, I let the PCB fabrication house choose the drill sizes based on the files I uploaded. They chose a drill size just a tiny bit too small to accept the square section header pins. I tried drilling out the holes but it recked the through hole plating and ended up looking a bit of a mess. So upshot was the first revision had to be wired but V1.1 can use the headers.

On holiday in Spain at the moment, really clear skies wish I had my Astro gear. However, after the girls have finished packing I only had room for my toothbrush and a pair of trunks :)

Clear skies,

Dave

[wasyoungonce]

Hi Dave

Installed PC driver 3.5 from your site, installed ok (it stated on the ASCOM install routine..."...install PC driver ver 3.5"), but when using your older client.exe I noticed my PC driver was identified as ver 3.4...yet I installed 3.5. I re-installed 3.5 again (twice) same issue.

See screen grab.

In properties tab it displays PC driver 3.4! yet I installed 3.5! I'm only using client for testing...sorry I didn't try focusmax. Edit: same in focusmax properties.

Brendan

[dtrewren]

Hi Brendan,

That's a bit strange ....

I suspect it will be one of two things. File version control went crazy (very unlikely) or operator (me) went crazy and didn't update the version variable before compiling :)

Soon as I'm back from holiday in very sunny Spain I'll recompile and upload.

Sorry about that .....

Clear skies,

Dave

[dtrewren]

Hi Brendan,

Back from holiday now so have had a look at the driver issue you reported. I have downloaded the latest driver and installed and can confirm it is V3.5 with the new client reverse checkbox.

I suspect I might know what your problem is. I think you may have a driver dependency situation when installing the new driver. This is 'usually' caused by having a client program active when installing the new driver. Because the client puts a dependency on the driver Windows cannot uninstall the old driver completely and leaves the .DLL in place. It's a safety feature but a PITA IMO.

- Close all client programs
- Uninstall the old V3.4 driver
- Check for the file 'ASCOM.SharpSky.Focuser.dll' in this directory
C:\Program Files\Common Files\ASCOM\Focuser
- If said file is present after uninstalling delete the .dll file

Install the new driver.

I can tell you have the V3.4 driver and not the V3.5 driver from your screen shot because it does not have the client reverse checkbox.

Hope that fixes the problem, please let me know.

You Aussies no what's good for sunburn - apart from playing in the sea with no sunblock on :rofl:

Clear skies,

Dave

[wasyoungonce]

Thanks Dave.

I found an uninstaller for sharpsky 3.4 driver in the C:\Program Files\Common Files\ASCOM\Focuser\....

I just used this and now installed PC driver 3.5.....many thanks. I was looking for the dir to find the dll ...didn't find it ..until now.

The new ver 3.5 driver has a .dll in the same location no uninstaller.

Have much on my plate at the moment so many thanks for your help and patience.

As for sunburn....always keep your swimming trunks on....lesson No1, when at the beach! I found that the hard way once, when young :wink2:.

[Astroman]

I am thinking of getting this project instead of an accufocus, seems to offer a whole lot more for little more money. Have PMed David re: pricing to Australia

Sunburn, get some Aloe Vera Spray, works a charm on sunburns....

[dtrewren]

Hi Brendan & Andrew et al,

You guys did make me chuckle even though my sun burn smarts a tad. I was actually snorkelling at the time - although complete with trunks, the thought of anything less makes me feel a little ..... ill. School boy error swimming about with back to the sun, tend to lose track of time and by the time I was out I was a little .... pink :)

The driver does generate an uninstall utility it should be in :
C:\Program Files\Common Files\ASCOM\Uninstall\Focuser\Sharp Sky

And is named imaginatively : unins000.exe

This is the .exe that Microsoft executes when you ask to uninstall the driver in the control panel.

Andrew I sent a private message (for some odd reason) I'm adding on an extra £5 for postage down under. It's about £3 in the UK and about £8 for Australia which I though was quite good as it gets there in about a week.

Clear skies,

Dave

[budman1961]

Wow, what a fantastic project.....Do you ship to the USA, and how much is the kit in US dollars?

Andy

[dtrewren]

Hi Andy,

Very pleased you like the design, thanks for the feedback!

Sure I can send to the USA, just a stones throw over the pond compared to the guys down under. I suspect postage will be about the same so the kit comes in at £73 or roughly $113. If you use PayPal you can simply set the currency you wish to pay in and the conversion is worked out for you...... such a great thing PayPal.

Send me a private message with your details and I can get a kit going transatlantic.

Cheers & clear skies,

Dave

____________________________

[dtrewren]

Hello,

Just a little note :

Just to keep the thread clean and non commercial please direct any questions regarding kit supply or pricing via personal/private messaging. That way the thread stays purely technical :D

Cheers & clear skies,

Dave

[garymck]

Hi,

just completed my Sharpsky focuser. All in all I would say that I spent about 4 hours putting it together. Everything worked first time apart from the manual control which I botched up with lousy soldering due to trying to solder a din plug (god I HATE din plugs) left handed as I have a broken right wrist. After replacing this plug which ended up looking like it had been attacked with a blow torch, it worked perfectly. If I can put it together then anyone can....best value astro purchase I've ever made. Dave also replied patiently to my pleading for help emails. Just have to get the motor to focuser connector bored to the right size for my focuser an I'm go.

cheers
Gary

[MrB]

Haha. Yes I hate them too.
I've been using a soldering iron since I was about 7, but I could not imagine soldering with my left hand! Nice work!

[dtrewren]

Morning Gary et al,

Excellent news, very pleased you sorted out your manual focus control - was scratching my head trying to figure out what might me the problem :D

I'm the other way around ..... born a left hander, they tried to beat it out of me as a child but still one of the minority. Soldering with my right hand would be like soldering on the end of a ten foot pole.

With regard the DIN plugs. What I do is assemble the PCB first, then plug the DIN plugs into their respective sockets and then solder the wires on while they are plugged in. Having them plugged in provides a stable platform so you are not chasing them all over the bench. Also the socket & PCB acts as a heat sink so the plug body does not deform with the heat and obviously the socket holds all the pins in place. If you don't use too much heat the plug might even come out of the socket after soldering to :lol:

The suns out and I can see sky in the UK ...... miracle !

Clear skies,

Dave

[wasyoungonce]

Dave and I spoke about the DIN plugs, the consensus is that at least these have some protection from moisture. The Alternative is RJ type connectors which offer little moisture resistance.

I'm not a great fan of the DIN/MiniDIN but hey they work and surprisingly well in this case and lock in position fine. Down side is almost impossible to line up in the cold & dark. Daub a locator paint mark on the connector and housing to show the key-way.

Just wish the mini DIN body back shell were a little shorter, that would help.

[dtrewren]

This is very true those DIN plugs can be a little fiddly in the dark while holding a large glass of red :) My controller is fixed to the mount and I leave the manual control permanently plugged in and then attached to the pier with a little square of Velcro.

I am not really doing any visual work, only photography and have the focus positions for various setups stored as pre-sets on my client. As a consequence don't really use the manual control very often. It is useful if the DSLR is on the scope and you want to get approximate focus using live view. Generally hit the focus pre-set and then nail focus with a mask. Then obviously forget the mask and have to do the first sub again :)

Clear skies,

Dave

[wasyoungonce]

I meant to say for those using ML stepper (re:Hurst) motors. When I 1st used the controller with this combo I got a lot of miss-stepping and motor buzz/chatter.

I had to set the "Period per step" (in ASCOM properties handling tab) from the std 35ms to around 60ms. Once done...all good.

Something to do with the way the Hurst is wound? This didn't happen with the cheaper ebay motor I tried.

Anyway just mentioning this so anyone else seeing this will know what to do.

[allan gould]

I've just started soldering David's controller and stepper motor system after receiving it mid week. I confess that my previous attempts at soldering were absolutely pathetic but I read the instructions and went through to the final steps. Amazingly i plugged it in and it worked perfectly first time without any drawbacks. Could not believe it, not because the kit was complicated but that I could do it with no previous soldering experience.
I was amazed at the versatility of the kit and how well it's been thought out.
My hats off to you David for such a brilliant kit, great web site and for making this available to the amateur community.

[dtrewren]

Hi Allan,

Excellent, very pleased to hear you got everything up and running ! Also thanks for the positive feedback, very much appreciated.

Yes soldering does take a little bit of practice. One of the main reasons for designing the PCB with through plated holes was to make the soldering easier as the holes are effectively tinned through the board. The downside of this is that it makes (in my opinion) it much more difficult to get a component out of the board once soldered in. Solder pumps and de-solder braid are less effective if the hole is through plated.

Horses for courses I suppose.

Good job & clear skies,

Dave

[wasyoungonce]

Easiest method to de-solder on a double sided PCBs.....cut the component off and just de-solder the left over legs.

Works a treat for ICs/resistors/capacitors etc but not so good for SMD's...you tend to twist the legs which can tear the pads off.

For this get some "Chipquick (http://www.chipquik.com/newsletters/cq_new_june_2004.htm)"....adds a low melt point to the solder joints. You can bridge the legs of an IC with this (form a blob) and get the legs * pads hot (well relatively hot but not hot enough to damage pads) at once and just lift up the IC. Works a treat.

If your not into "chipquick" you can get good hot air SMD de-solder stations cheaply from fleaby (http://www.ebay.com.au/sch/i.html?_nkw=hot+air+solder&_sacat=0&_dmpt=AU_B_I_Electrical_Test_Equipm ent&_odkw=hot+air+desolder&_osacat=0&_trksid=p3286.c0.m270.l1313) from $50.

Of course...junk any removed component, never re-use them.

With soldering....clean..clean and clean again. Clean your iron tip every joint and multi core solder (with a spray solvent). I did write a doc on this (to put on IIS) but didn't(don't) have a method to macro record of some action videos.

Anwyway...FWIW.

[dtrewren]

All very good advice :D

I definitely favour the method of chopping off the legs of leaded components and then remove the legs individually. As Brendan says the component is best binned anyway so the priority is to preserve the PCB and cause as little damage as possible.

The 'Chipquick' is an interesting product, that's new to me ! In the past when removing SM devices I have used a heat gun and found this very effective.

Luckily, I have a secret weapon if all else fails ..... it's called a 'Rachel'. She's a contractor at work employed to perform board modifications and fix boards. The boards are ten+ layers with features I can barely see - if she can't fix it .... it goes in the bin :(

[peter_4059]

I've been thinking about changing to a stepper system for a few weeks now and after looking into this I've decided to give it a try. Ordered a kit today and can't wait to get hold of it.

Dave is doing a great job developing an excellent product and offering it to astronomers at a very reasonable price. Thanks!

[dtrewren]

Hi Guys,

Just a note for anyone that might be using/interested in the SharpSky client software.

I have made a couple of modifications :

1)
To make it clear where the focuser has last moved to any 'Go' button pressed is highlighted in ..... well a Coral colour in sympathy with antipodean reefs :D (suggested by Peter, the feature not the colour)

2)
I have added an emergency HALT button. Whenever the focuser is 'moving' the HALT button will stop movement immediately. Current absolute position when halted is preserved.

Latest V1.5 version is live on the website :
www.dt-space.co.uk/SharpSkyClient

The client is ASCOM compliant and will therefore work with any such focuser including the ASCOM focuser simulator.

I have tested the client post modifications, but if any problems are found please let me know.

Cheers & clear skies,

Dave

[allan gould]

New software works well Dave. Many thanks for that

[dtrewren]

Cheers Allan - thanks for the feedback :)

Clear skies, Dave

[allan gould]

I forgot to note that I did not have the problem that Brendan did with the Moonlight stepper. It purred like a kitten with no motor chatter and thus did not have to alter the step period.m

[dtrewren]

Hi Allan,

Excellent new s on the MoonLite stepper. I can't remember if Brendan bought an actual MoonLite stepper or sourced the same motor as they used (Brendan ?).

I essentially found the step period using a simple empirical method, ie just reduced the period until the motor became unhappy and started missing steps and then added 10% to the value. That came out to ~35ms for the motor supplied with the kit.

Those MoonLite Hurst motors are very nice and they are always a pin compatible upgrade option if you have some spare cash.

Does the MoonLite motor have a mechanical clutch which can release the drive ?

Clear skies,

Dave

[allan gould]

Yes, Moonlight have now incorporated a slip clutch into their attachment to the focuser. So now it's easy to do a rough manual focus, tighten the clutch and then focus critically. Love it with your controller but I'll have to get the temp compensation working when I can set up the components.

[dtrewren]

Hi Allan,

That's a real nice feature having a clutch :) The temperature compensation shouldn't be hard to set up. One obvious thing to point out and it can cause a bit of head scratching is to make sure the compensation is running in the correct direction.

So as the scope cools it contracts so the focuser should wind out to compensate and keep you in focus. If you think it's running in reverse there is a switch on the SharpSky driver window under 'Temperature compensation' called 'Direction reverse'. Once checked this reverses the direction of only the temperature compensation.

Easiest way to check is set a really big 'steps/degree' value say 100 and then cool the sensor with something .... a bag of frozen peas :D and check the focuser moves in the correct direction.

Cheers & clear skies,

Dave

[allan gould]

Ah! The old frozen peas trick - will do. Thanks for the tips Dave

[dtrewren]

Hi Guys,

While you chaps are pushing up the Zzzz or hopefully imaging I decided to make a little video.

I have had a few questions regarding temperature compensation so decided to make a short video just showing the SharpSky temperature compensation actually operating in practice and upload the result of the logged data. I hope is clarifies the operation a little :)

Video : http://www.youtube.com/watch?v=b-7uyLQSZ4o

The file logged during the demo :
www.dt-space.co.uk/SharpSky/source/SharpSky_templog.txt

Any questions or comments please fire away.

Clear skies,

Dave

[wasyoungonce]

Thanks Dave. But what I want to know.....Wot does the Mrs dtrewren think of you using her peas?:lol:

[dtrewren]

Your not going to believe me Brendan but those are actually my own private bag of peas I bought specifically for temperature testing - the normal family peas have a habit of being eaten just when I need them most :rofl:

[allan gould]

David
You are costing me a fortune!!! After building your controller for the stepper I'm going to have to replace the DC motor on my 10" RC with a stepper motor and that will entail a new back plate. Sigh, just more money but I love your controller so much that that it's necessary.

[dtrewren]

:lol: sorry about that .... but you are buying the best in terms of motors assuming you go for another MoonLite ?

[wasyoungonce]

Actually the DIY install ML steppers are quite cheap, you get a Hurst geared stepper inside and a fully milled housing with motor clutch system.

Hurst motor alone is ~$95usd.

Beauty of all this is that if you want you can change your hurst motor for better step accuracy ...lets say if using a shorter FL scope (Smaller CFZ) of lets say F4.0.

[peter_4059]

My kit was waiting for me when I arrived home this afternoon. Very nicely organised into a number of labeled plastic bags making identification of the parts a breeze (thanks Dave).

I've soldered all the parts onto the PCB and powered it up this evening and get the "heatbeat" light so all looks good at this stage. I now need to make up the leads, drill the various boxes and put it all together.

I'm hoping it will work with a longer (3m) DB9 cable between the controller and the stepper so I can keep the power and USB connections in my box of gadgets beneath the tripod.

[troypiggo]

Wow. That was quick.

[hikerbob]

My kit arrived last friday, got the board soldered together Saturday morning and then had to move onto other things. I got around to powering it up this evening and the heartbeat led worked first up.

I then soldered up the encoder and it's plug, connected the motor directly to the board and gave it another test. All working as expected.

I'll get on with the cut out's shortly and have a think about mounting the motor.

Bob

[dtrewren]

Hi Bob,

Excellent news, good job - thanks for the progress report !

Any hints, tips or improvements I'm all ears. Also if you get chance to add a line or two on the forum that would be good.

Hope the mechanics go to plan :)

Cheers & clear skies,

Dave

[peter_4059]

Dave,

I have some questions about the client operation:

1. Should the absolute position indication change as temperature compensations are being made - the motor is changing position however the indicated absolute position remains constant.

If you click the "go" button for the reference position after temperature adjustments have been made it returns to the unadjusted position. I guess what this means is that a reference position is associated with a temperature. Under what circumstances would you use the "go" for the reference position - is it to get you in the ballpark at the start of the run?

2. It looks like the hand control works independent of the software interface - ie if adjustments are made to the focus position using the manual control the indicated absolute position does not change.

3. It looks like the temperature indication only updates if you click the temperature button - is the button doing some other function and why not update temperature indication automatically?

[dtrewren]

Hi Peter et al,

Thanks for your observations. The client is working as originally intended but based on your comments and observations I could see room for improvement and the scope for some additional functionality.

To this end I have put my coding hat back on and have performed a few modifications which I hope you will like :)

Addressing points 1 & 2 :
The absolute position is now 'live'. Every second the position is updated and will reflect the absolute position including changes made using the manual control and/or temperature compensation. The manual control is intimately hooked into the software. When the manual control is used the PIC firmware moves the motor by the user selected number of steps. This information is also stored locally in EEPROM and reported to the PC driver via the USB connection. Once a second the client polls this information from the driver and the corrected position is reported to the client via the ASCOM API and subsequently displayed. Something similar occurs with temperature compensation but is quite a bit more involved.

API - Application Programming Interface.

Addressing point 3 :
The temperature window is now also 'live' and reports the temperature once per minute. If the 'Temp Now' button is pressed the current temperature will be displayed immediately.

The 'Go' buttons will take you to the value associated with that button irrespective of temperature compensation. The idea is you Go to a filter position, check & fine tune focus and then enable temperature compensation if required. I always use my luminance filter as the reference position and therefore would hit 'Go reference' if I wanted to return to the luminance filter.

New checkbox feature :
I have added a temperature compensation enable/disable checkbox. This checkbox is only available if 'temperature compensation available' has been checked in the driver. If you check/uncheck the enable/disable button on the client this state will be mirrored and remembered in the driver and visa/versa.

The new V1.6 version of the client is available for download via the website:
www.dt-space.co.uk/SharpSkyClient

I hope I have explained operation clearly ? If there are any questions, additional questions or bugs found (perish the thought :)) please let me know.

Cheers & clear skies,

Dave

[peter_4059]

Cheers Dave. I'll check that out today.

I got the stepper installed on my Meade ED80 yesterday however the focuser isn't going to be adequate for the weight of the QSI. If I tighten the focuser tension so the drawtube doesn't slip the stepper can't overcome the friction and if I reduce the tension so the stepper is happy the drawtube slides out. I have a solution though and I've been looking for an excuse ;)...

http://www.focuser.com/cgi-bin/dman.cgi?page=productdetail&plugin=dstore.cgi&product=CF

[dtrewren]

Hi Peter,

Thanks for the feedback. I have a few questions regarding your focuser setup. Not had a problem with payload limit so far so would be nice to know the limiting factor.

- Roughly what is your payload weight ?
- It there significant focuser resistance even without the payload ?
- Is the motor coupled via the 10:1 fine focus ?

I do have another possible solution. I have another motor, same type as the supplied motor but it's big brother. The alternative motor on paper has about three times the pull in torque. I don't supply the bigger motor as standard just because it's usually over kill and is more expensive but still beer money (~£10) compared to the MoonLite.

I can send you the bigger motor to try out before going for the MoonLite ?

Cool, be interested to hear what you think regarding the software updates. I have had the updated client running all night with temperature compensation running and it's all very happy.

Clear skies,

Dave

[peter_4059]

Dave,

My Meade is one of the old ones and it only has 1:1 focus mechanism. This is probably the main issue. The camera is a QSI 683ws-8 and it weighs about 1.6 kg. I never had any issues with the QHY8 however the QSI camera is quite a bit heavier so I think the focuser is going to be an issue regardless of the stepper. The resistance is adjustable however it needs to be done up pretty tight to stop the draw tube sliding out under the weight of the QSI. I've got a Moonlite with a DC motor on my 10" Newt and I'm thinking about upgrading this to a stepper version in the near future. This focuser/DC motor handles the QSI without any issues.

I downloaded the new version of the client today and I'm planning to have a play with it tonight.

Peter

[dtrewren]

Hi Peter,

I had a similar issue with the stock focuser on my ED80 when I upgraded to a QHY9M+FW+TS FF. I could get the draw tube not to slip but had to nip up the tensioner quite a bit. This made the entire focuser movement quite tight. In the end I came to the conclusion that the focuser was operating at the limit (maybe a bit beyond) of it's payload capacity. So I upgraded the focuser of the ED80 & ED120 and this really solved the problem. The draw tube no longer slips but the travel is smooth and not tight. Also there is a 10:1 control which is coupled to the stock motor I have been supplying with the SharpSky kit.

Obviously, MoonLite focusers are in a different league but the budget wouldn't really stretch to two of these beasts. The motivation for making the SharpSky controller pin compatible with MoonLite was to permit an easy upgrade path from budget stepper motor and bracket to MoonLite/Robo. However, now I have motors and brackets fitted to my scopes the focusing performance is great so will stick with the current setup.

I think like many people I'm not sure how I managed before fitting remote focusing - for me it certainly makes the imaging experience more enjoyable :)

Cheers & clear skies,

Dave

[peter_4059]

The changes to the client are great Dave. Much more intuative now. Thanks.

[dtrewren]

Hi Peter,

Excellent, thanks for testing it out and the feedback. Anything else that you think might make it easier to use or might be useful let me know.

Cheers,

Dave

[peter_4059]

The new tab layout looks good Dave.

I've been playing with the temperature compensation and with the filter presets tonight and have a question about how these interact.

I would have thought the desired behaviour would be to allow the temperature compensation to take care of the absolute position during the night and for the filter offset to look after the difference from one filter to the next ie:

1.I focus on the Lum filter at the start of the night at say absolute position 3500 and set this as reference. Offest for this filter (filter 1) = 0
2. Temperature compensation moves the absolute position as the temperature drops (in my case the absolute position is increasing=focuser in). Assume the absolute position drops by 20 steps to 3480.
3. I change to the next filter say red with an offset of 10 steps relative to the lum at constant temp by clicking go for that filter. I would expect the absolute position would move to 3480+10=3490.

I think what is actually happening is the focuser moves to ref+10=3510. This means I would now need to refocus for filter 2 as the reference position was set at a higher temperature. The same would apply for each filter change if the temperature changes.

Let me know if I've got this all wrong :question:

[dtrewren]

Morning Peter,

Yes the behaviour you have described is the current operation. So when you go to a new filter position you will lose the current temperature offset.

It's a tricky problem because there is no mechanism to pass back from the driver to the client the offset. It is only possible to pass the current absolute position. Therefore the client is going to have to work out keep track of the offset generated by temperature and then add the offset to any subsequent filter position. This new corrected position now becomes the new temperature reference point for the future calculation of accumulating temperature offsets.

I have had a bit of a think about it and come up with a mechanism. I think it might be a good idea to have a new metric on the client displaying current temperature correction as a +/- value. So this is the value that gets added to any 'Go' position the user selects. This value is reset to zero if temperature compensation is disabled or a new reference position is loaded. Also there can be a reset button allowing the user to reset or change the compensation value manually.

So essentially as long as compensation is running any change of position with respect to the reference position will have a temperature compensation offset added to it. I will write driver code to calculate and keep track of the offset over time, this will be transparent to the user.

It's still a bit tricky, I'll have a crack at it tonight might take a couple of hours to get it to fly :)

By the way your replacement main enclosure is heading south.

Cheers & clear skies,

Dave

[dtrewren]

Hi Peter,

I have thought of one small problem ......

There currently no way of differentiating between a temperature driven movement and a movement generated by the user moving the manual control. So with the tracking system I proposed in the previous email if the user were to use the manual control this would be misinterpreted as temperature compensation and added to the offset.

There is a way to stop this but I would have to change the PIC code and all the PICs sent out would need reflashing - something I really wanted to avoid. So I think a message will have to be displayed when temperature compensation is running warning the user not to use the manual control.

Cheers,

Dave

[peter_4059]

Dave,

Would it be possible/correct for the client to calculate new motor position as current absolute position - current filter offset + new filter offset. This would then take into account the current temperature offset and any changes to the manual control?

Peter

[dtrewren]

Hi Peter,

Yes indeed that's good solution if you want to keep all the temperature & motor movement in the equation.

So if you have your filter offsets as say L, R, G, B hitting go on any of these takes you to that offset + temp + manual control. Hitting reference Go always takes you to that absolute reference irrespective of temp/manual offsets.

Sound sensible ?

Cheers,

Dave

[dtrewren]

Hi Peter et al,

I have made some further modifications based on Peter's suggestions.

- By default when a filter 'Go' button is pressed the focuser moves to that filter offset relative to the reference position. However, if temperature compensation or the the manual control has taken effect that offset will also be a part of the movement. This makes it possible to move from filter position to filter position and preserve the cumulative temperature offset and/or any manual adjustment.

- A new checkbox has been added called 'Ref Lock' once checked this causes the focuser to move to the filter offset with respect to the reference position regardless of any temperature or manual control activity.

- Hitting the 'Go' reference always returns the focuser to that absolute reference position.

The current V1.8 version is available for download.

Clear skies,

Dave

[garymck]

Hi Dave,

is it possible to have two of the focusers operating at the same time. Imagine a situation where you had one scope taking color, and another taking mono of the same object. Both need to be focused and temp compensation possible provided.....maybe need separate usb id's????

just dreaming a bit at the moment as I'm about to construct a mini roof top observatory.....

cheers
Gary

[peter_4059]

Dave,

That new version is working well. One small thing I noticed is if you click any of the focus control buttons on the client it resets the colour on the filter "go" buttons back to grey so you can't see which filter you last selected. Was this intentional? The movement of the stepper is still correct when selecting a different filter despite this.

I also had a couple of thoughts regarding the client tab layout:
I think the ref position controls would be better on the focus control page as this is the page you are most likely to be on when the ref position is set. Also the reference position will most likely be the lum filter and the go button for this filter is already on the filter position tab.

Once the ref position is set I will most likely switch to and stay on the filter position tab. It would therefore be good to have the temperature comp controls and temp display on the filter positions tab. Finally I think it would be nice to have the absolute position indication replicated on the filter position tab so you can see what's going on.

Just my thoughts - please feel free to ignore if you've heard enough bright ideas from me!

Peter

[dtrewren]

Hi Peter,

Not at all, good suggestions based on real usage :)

I have incorporated your suggestions into the client and have uploaded V1.9 onto the website.

See what you think and let me know.

Cheers & clear skies,

Dave

[dtrewren]

Hi Gary,

Apologies for the delay .... that's a really good question regarding multiple focusers operating at the same time. I have been sketching stuff out trying to figure out how it might be best achieved, also spoken to the guys that designed the ASCOM platform to ask their advice and got some really helpful feedback (as is the norm).

The bottom line is .... it's not all that easy as I get the impression the platform was not really designed to support such a feature. However, just because it's hard and probably won't work is no reason not to do it anyway :) plenty of head shaped dents in the wall disprove that !

I think the simplest solution might end up essentially a duplication of resource. So two motors and two controllers with two separate USB connections. Each controller is running the same PIC firmware but has a hardware jumper to select controller 0 or 1. You would also have to install two drivers one for each controller. Finally you invoke two client programs and select 'SharpSky 0' on one and 'SharpSky 1' on the other.

It's not ideal but I think it could be made to work.

It would be possible to use a single controller but this would obviously result in a complete hardware re-design. I don't know of a commercial product that provides dual functionality (anyone know of one ?) this maybe because there is low demand for such a feature and it would increase cost.

It is a very interesting problem ... I'll look into how much work is involved.

Cheers,

Dave

[allan gould]

This is getting too fast for an old fellow to keep up with. Great work Dave and Peter.

[wasyoungonce]

I was thinking the same...quick service indeed:thumbsup:

[peter_4059]

Dave,

I've downloaded V1.9 this afternoon and really like it now. The new layout is a lot better IMHO.

I've tried out all the buttons and combination of switching temp compensation on/off, moving it with the on screen buttons and the hand controller and from what I can tell it is making all the right moves.

I'm a little confused about when I'd need to use ref lock - it seems to do the same thing as hitting the ref position go button?

Thanks for the quick turnaround. Will spend more time testing this weekend.

Peter

[dtrewren]

Hi Peter,

Excellent, pleased you like the layout :)

The Ref lock :
This button, if checked, removes any component added due to temperature or manual control. So as an example :

Ref lock : unchecked (default)
Abs position : 25000
Reference position : 25000
Filter 1 offset : +100
Filter 2 offset : +200

Hit Filter 1 Go : Abs position 25100
Hit Filter 2 Go : Abs position 25200
Hit Reference Go : Abs position 25000

Temperature compensation adds in +5 steps

Hit Filter 1 Go : Abs position 25105
Hit Filter 2 Go : Abs position 25205
Check Ref lock button
Hit Filter 1 Go : Abs position 25100
Hit Filter 2 Go : Abs position 25200

So with Ref lock checked all filter movements are with respect to the reference position only and any temperature/manual movement is lost when you move to a new filter position or even the same filter position as with the example. This allow you to move to an absolute filter position and start compensation from the point fresh clearing out any previous movement.

Hope that makes sense ?

Thanks for taking a look, much appreciated !

Cheers & clear skies,

Dave

[peter_4059]

So just to clarify the ref lock I'm assuming I'd see:

Hit Filter 1 Go : Abs position 25100
Hit Filter 2 Go : Abs position 25200
Hit Reference Go : Abs position 25000

Temperature compensation adds in +5 steps

Hit Filter 1 Go : Abs position 25105
Hit Filter 2 Go : Abs position 25205
Check Ref lock button
Hit Filter 1 Go : Abs position 25100
Hit Filter 2 Go : Abs position 25200

uncheck ref lock button

Hit Filter 1 Go : Abs position 25100
Hit Filter 2 Go : Abs position 25200

temp comp adds +5 steps
Hit Filter 2 Go : Abs position 25205
Hit Filter 1 Go : Abs position 25105

does that sound right?

Peter

[dtrewren]

Hi Peter,

Absolutely right, just been through the sequence and that is exactly what what you see.

With the Ref lock unchecked as you move around any compensation and/or manual intervention is added to the absolute position. When you check the Ref lock compensation and/or manual input is only effectively valid for the current filter as soon as you move to a new filter the additional input is discarded.

By manual input I mean either via the software GUI or the manual control.

Cheers,

Dave

[rjweng91]

Dave,
Thank you so much for taking the time for making this kit, I only burnt my finger once. :) Tested it out last night with Focusmax and MaximDL; they worked great.

Thanks
Bob W

[dtrewren]

Hi Bob,

That's excellent news, always good to get at the end of the day. Was that trying the focuser out in anger while imaging ?

If it's any consolation I also burnt my fingers this evening. After drilling & tapping the beam couplers I wash them in warm soapy water to remove the cutting grease and then bake them at 150 degrees C for fifteen minutes to dry before inserting the grub screws.

Observation : very hot aluminium looks the same as cold aluminium but feels very different :lol:

Clear skies,

Dave

[peter_4059]

I've recently upgraded to a win7 64bit laptop and have started to have some issues with the stepper controller. If I try to move up to 100 steps there are no problems. If try to move 1000 steps or more I get an error "Cannot access a disposed object" and the focuser disconnects. (I've been using sequence generator pro to control everything). I haven't tried this with the Sharpsky client yet so I'm not sure if the error is with the driver or with SGP however this has only started being an issue since I changed to win7. On some occasions when the focuser disconnects it leaves the stepper motor running and I have to remove the USB connection to stop it.

It is not a massive deal as normal focusing only requires a move of 20 steps at a time however if I want to rack the focuser back in it can be tedious to move 4000 steps in 100 step increments.

Any thoughts?

Peter

[dtrewren]

Hello Peter,

That's an interesting one, not seen that one before. The only tricky problem is that I don't have a machine running W7 64bit .... at the moment. Going to see if work IT can knock me up said machine so I can debug the issue. Had a look on-line and there seem to be lots of people getting a message like this and lots of misinformation flying around as to the reason. I will look into it, if I can replicate the problem I can fix it.

Small favour :
If anyone else is running W7 64bit with any client program and fancies having a go at a large move say 2000 steps I would appreciate the feedback just to see if it's a universal problem or just particular to Peter's setup.

I'll get onto it :)

Clear skies,

Dave

[peter_4059]

Hi Dave,

I tried it out today with the SharpSky client and didn't have any issues. I think I know the answer but can you confirm the Sharpsky client is using ascom to drive the focus controller?

The issue seems to be related to Sequence Generator - if I do too many small steps close together or one big lot of steps it seems to generate this error.

It is not a big issue as I don't have a problem with a few small steps so the autofocus works fine.

There should be a few others that have win 7 64 bit and your controller and some are using Sequence Generator so shouldn't be too hard to get some testing happening.

Cheers,

Peter

[dtrewren]

Hello Peter,

This is very interesting :)

Yes, the SharpSky client is just another ASCOM compliant client. So it connects the the driver in exactly the same way as any other client using the same API. You can connect the SharpSky client to any ASCOM compliant focuser for example the focuser simulator and it will work.

What to do .....

I think I will carry on with my plan of replicating the problem on a machine here and see what I can figure out. Trouble is with this software business is there are always many ways to skin a cat. If it looks like the error is being thrown in SGP I will have a chat with the guys there and see what can be done to stop the problem.

The SharpSky driver is fully ASCOM compliant and passes the conformance checking where large movement tests are performed. However, projects are about issue solutions and not blame so it must be fixed.

Where is that IT guy when you need him !

Clear skies,

Dave

[peter_4059]

You've got me thinking now Dave. Perhaps I should connect SGP to the focus simulator and see if I get the same error?

[peter_4059]

Just tried SGP with the ascom simulator and it works without any issues. I should also mention here I have seen a couple of error dialogue boxes - the one I mentioned earlier "Cannot access a disposed object" and another "Object reference not set to an instance of an object". Not sure if this casts any more light on the issue?

Peter

[dtrewren]

Hi Peter,

yep, I just tried the simulator with SGP and it worked fine. I think the issue is to do with time. When connected to the simulator a movement of say 2000 steps is virtually instantaneous. However, when connected to a real focuser 2000 steps can take some time to execute.

While the motor is moving there is a chain of command. The PIC is aware the motor is moving because it is physically driving the motor. So the user initiates a move and client sends the command to the driver via ASCOM. The driver interprets the command and sends a command to the PIC via USB. The PIC receives the command & starts the motor moving. Now the client wants to know what the motor is up to so polls the driver for motor status, in tern the driver polls the PIC for motor status. PIC reports motor moving to the driver, driver reports to client and client reports to user .... an so on until the move is complete.

So if the client is waiting for something to happen and it doesn't happen or takes to long it might get upset and throw an exception or error. The part I'm a bit confused about is that the ASCOM conformance checker checks for correct driver response and is happy. So I am not sure why SGP is getting upset.

These sort of problems are what make development interesting :)

Dave

[dtrewren]

Hello Peter et al,

I have just been doing a few experiments. Using W7 (32bit) and XP I performed large moments of 5000 steps using APT, SGP, ImagesPlus 5.0 & my client all without issue. So the issues does appear to be a platform 64bit OS problem.

Just a small point. you might notice when doing a very large movement to on occasion the motor will stop for about 1/2 second and then continue to move. This is normal and is caused by the client requesting a temperature update if the probe is fitted. The probe can take about 1/2 second to return a value so things stop while it is being accessed. No motor steps are missed just a slight pause in movement.

Clear skies,

Dave

[peter_4059]

Dave,

I'd also concluded it was a time related issue. Definately not a show stopper but it would be nice to resolve.

Hopefully some of the other users are able to test and help get to the bottom of this.

Peter

[dtrewren]

Hello Peter et al,

I have just had a very interesting hour on a W7 64bit machine (I really must get out more :) )

- Installed the SharpSky driver
- Installed my client
- Installed SGP (latest version)

- Tried my client - no issues all good any number of steps
- Tried SGP with 100 steps - no issue
- Tried SGP with 1000 steps ........ whoops fell over

Same error message Peter is getting, I won't repeat Peter's report but my experience was the same.

- So tried SGP 100 steps again - all good
- Tried SGP 101 steps - whoops, fell over as before !!!!!

So, and this is the interesting bit ! I then decided to install another client, in this case I installed APT. Unfortunately, APT wouldn't install in the 64bit environment. The APT installation realised this and automatically un-installed itself cleanly.

NOW - I then tried SGP again ...... fixed ! Any number of steps in any direction always worked. I removed my driver and SGP and re-installed both everything working fine still any number of steps :)

This is what I think & I'm more than happy to be corrected :
I think SGP has a small issue with the 64bit environment, possible a run time library problem or something like that (bit too hard core for me). When APT tried to install it brought with it some run time library modules or made some change to the environment probably installing some x86 stuff that SGP is relying on. So after the APT failed install SGP subsequently has access to whatever it was missing in the environment and is now happy. I have been unable to replicate the SGP problem following the failed APT installation.

So, Peter you could try an APT installation (it's free) and see if this fixes your problem. I will report my findings to the SGP boys and see what they think.

Let me know how you get on ....

Clear skies,

Dave

[peter_4059]

Interesting Dave. Which version of APT did you use - was it the free version of V1.93?

Peter

[dtrewren]

Hello Peter,

Indeed, simply the demo version 1.93 :
http://www.ideiki.com/astro/Download.aspx

I am not suggesting this is a solution to your W7 64bit issue, but an interesting experiment none the less. I have joined the thread you initiated on the SGP forum with the hope of getting to the bottom of the problem wherever it may be. Been very impressed with the SGP forum and the level of feedback & support. I am going to generate a debug version of my driver that does not require the hardware so that the SGP developers can test out the interaction between client & driver. I am hoping the issue is not with the driver but am happy to stand corrected - either way it gets fixed.

Be very interested to see what happens if you attempt an APT installation and whether this fixes the issue with SGP ......

Cheers & clear skies,

Dave

[peter_4059]

Hi Dave,

I tried installing APT however it installed normally but did not resolve the SGP issue - no idea why my installation is different! I've now un-installed it and had a look at windows restore however it doesn't show any APT files as remaining after the uninstall.

Peter

[dtrewren]

Morning Peter,

This is all very strange, windows environments are a bit of a minefield. I have created a debug version of my driver and passed this to Jared at Main Sequence Software. This debug driver looks identical to the normal driver from the client point of view over the ASCOM API but has all the hardware specific USB communications stubbed out. This allows Jared to install and test the driver without any hardware connected.

I'll be very interested to see what he finds :)

Cheers,

Dave

[peter_4059]

I agree Dave. Seems each pc is a bit unique. I'm going to give it a try on my Win7 32bit machine tomorrow but I've realised I can always use your client to rack the focuser in/out if necessary. I'm pretty sure the SGP guys will figure out what's happening with this. They have been incredibly responsive to everyones issues and requests so far.

I will be interesting to see if the issue happens with your debug driver - does the motor delay get reproduced?

Peter

[dtrewren]

Hi Peter,

Yes it will be interesting. I don't really mind where the issue is as long as it gets found and fixed. If it is in the driver I'll probably end up learning something new which is always good.

No the motor delay is not reproduced at the moment. I am now thinking it's not about the delay. When I was reproducing the fault it was the 100 to 101 boundary that caused the issue ... very odd. The SGP guys did mention they have a bug, something to do with the step size being 100 seem like too much of a coincidence. I thought maybe my driver was incorrectly reporting the step size and generating this bug they mentioned but I can't find any evidence of that. I'm sure Jared will spot it and we can tie it off.

As a matter of interest do you also find that 100->101 causes the problem?

Cheers,

Dave

[peter_4059]

Dave,

I've found it occurs at bigger steps (between 600-800) however it isn't consistent. Never an issue below 100 unless I press the move button too fast/too many times.

Peter

[dtrewren]

Hello Peter,

I'm sure you picked this up from the SGP (Mainstream SW) forum. I have fixed your problem with SharpSky, SGP & W7 64bit - it was fun. Went to my parents as Mum has a 64bit machine, plugged everything in and sure enough there was your reported SGP problem ! Installed all the C# developer tools and got to work. I am still not sure if the problem is not six of one and half a dozen of the other. Basically SGP is doing something I was not expecting and have not seen before with other clients and my driver wasn't happy with it. Why it only happens on a W7 64bit machine I have no idea so am hoping the Mainstream guys might know more.

Upshot is I have made the driver more robust in the offending area so with a new driver your problem should be history. If you could afford me a little more time that would be great. I just want to do a bit more testing just to make sure nothing nasty has crept in.

Cheers & clear skies,

Dave

[peter_4059]

Great news Dave - thanks for following this up. No rush - won't get a chance to do any imaging until next weekend in any case.

Peter

[peter_4059]

Dave,

I found your message earlier in this thread on how to uninstall the driver and now have the new one installed. Tested it with SGP and all is working perfectly now. Thanks!

Peter

[Cloudyagain]

Received my kit earlier this week from Dave, took just over a week to get here. Easy to construct but I used a different motor to what Dave supplied and I required some help to get it running properly. Dave provided prompt advice and after a couple of emails all is running perfectly.

Great kit and software, excellent service, highly recomended.

Thanks Dave for making this available.

Neale.

[dtrewren]

Hello Neale et al,

Great news, thanks for the feedback !

On the motor front any 4 phase unipolar motor should work fine with the SharpSky controller including the MoonLite Hurst motor. Even though motors have similar specifications due to variations in mechanical construction their response to being driven can be somewhat different. In order to support a wide range of motors I included a motor drive period parameter on the SharpSky properties window. This defaults to 35ms which gives good torque and speed for the motor I have been using. For Neale's motor this had to be increased to 60ms for smooth operation.

I usually increase the value to about 80ms and then reduced until the motor just starts missing steps or chattering and then add 10%.

Again, good job.

Cheers & clear skies,

Dave

[Karls48]

Today I got around to put together SharpSky kit I received from Dave few days earlier. Kit now include larger stepper motor and pre-made Mini DIN leads. Real bonus for me as my hands is not steady as it used to be and I don’t see that well. In no time PCB was finished although I did more guess then see, where I solder. But then I got over 45 years experience in repairing and manufacturing electronics. On power up everything worked as it should. I decided not to use LEDs except the heart beat one. My scope and mount already resembles a Christmas tree and I did not want to add more flashing lights. All what remains to finish it off is to manufacture focuser bracket. But it is very hot in my tin garden shed I use for mini workshop. Maybe tomorrow. The kit is one of the best I have ever seen and recommended to anyone who wants remote focuser control.

[dtrewren]

Hi Karl,

Fantastic news, a new toy just in time for Christmas :)

Very pleased you liked the kit - half the fun is in the building ! Be very interested to know how you get alone using the design in anger and any suggestions very welcome.

Have a great Christmas !

Cheers & clear skies,

Dave

[technofetishism]

hey dave, seeing some issues with ascom which i think is to do with the sharpsky, both with the sharpsky client and SGP. most nights at some random point, the focuer stops responding to any communications and requires ascom to be complelly shut down to come back to life. this ive seen happen even when not sending commands.

any thoughts?

[dtrewren]

Hi Nick,

Apologies for the delay, been away at the in-laws.

Mmmm, that's not great news. I have just finished a 24hr soak test with MaxIm DL and have just started a similar test with SGP. I have had issues with SGP pro in the past but thought everything was now running smoothly. SGP uses lots of multi-threading and it's a little difficult to see exactly what is going on sometimes.

I will complete a soak test and see what I can find. I assume you are using the latest version of the driver V3.8 ?

Cheers,

Dave

[technofetishism]

yep, to the best of my knowledge 3.8

[dtrewren]

Hi Nick et al,

Thanks for you patience, I have been looking into your issue with SGP. I am confident the problem is now resolved. This is what happened .... over the last couple of driver versions I have been making behind the scenes change to make the driver 100% ASCOM 6 and and clean as I can. However, I think that one such change has introduced a problem which I intend to follow up with the ASCOM guys. Upshot is I hope to have fixed the instability and have uploaded a new V3.10 version of the driver to the link on the SharpSky Kit website. I have soaked tested this version over a 24hr period with SGP & MaxIm DL.

http://dt-space.co.uk/SharpSky_Kit/

The new driver has a new feature under the 'hardware control' panel that allows the user to pre-set the focuser position to any arbitrary value. This does not move the motor but simply changes the value reported in the client to a value you want to see or maybe a zero point. Also the maximum range of the focuser has been extended from 50,000 to 150,000 steps.

Please let me know if the new driver version fixes your issue.

After closing all ASCOM applications uninstall the previous driver before installing the new version. You should see version 3.10 in the SharpSky setup window prior to connection.

Cheers & clear skies,

Dave

[technofetishism]

Hi Dave,

So I think there might be a firmware bug or another driver bug, ive currently got ascom connected to the sharpsky kit, telling it to dance around until for some reason it now says when in sharpsky setup via the ascom chooser, PIC firmware version 0.0 and it wont do any movements. However it does not cause an ascom driver crash (yet at least.)

reconnecting usb clears it up, but it does not throw any errors prior to that that are visible

[dtrewren]

Hi Nick,

Have you got it sorted ?

Once installed the V3.10 setup screen will look as attached screen shot with default values for MaxStep and Max focuser position at 150,000. Also you should see the new field 'Initial focuser position' with default value of 25000 for a fresh driver install. PC driver version should = 3.10 as screen shot. The reason Max Increment is at 50,000 is this is the largest single step jump you can make in one go.

If you don't get the above it's possible the old driver did not uninstall due to a client dependency, ie a client was open when the old driver was uninstalled preventing Windows from uninstalling cleanly - this happens a lot and is a bit of a pain. Check all clients are closed before uninstalling the old driver.

Let me know if all is good .....

Cheers,

Dave

[technofetishism]

Can the max increment of focuser also be able to be set to 150,000. Using zero focuser from SGP stops after 50,000 steps but still sets the focuser position to 0.

[dtrewren]

Hi Nick,

Currently the max increment is limited to 50,000. So you can move by 50,000 steps in one single movement. This value is passed to the client so SGP should not allow you to move by more than this limit.

Do you want to move by more than 50,000 in one go ?

[technofetishism]

I dont think this is just a SGP bug, as it seems to occur with the sharpsky client as well.


IN SGP
Using focus control in there, focuser currently set to zero position.

If I tell it to step out 32,768 steps. No movement occurs. Position is set to 32,768.
If I tell it to step in 32,768 steps. No movement occurs. Position is set to 0.

If I tell it to step out 32,767 steps. No movement occurs. Position is set to 32,767.
If I tell it to step in 32,767 steps. Movement occurs and Position is set to 0.

I cant get an outward movement to occur at a number higher than 32,761 (though that number is due to backlash setting i believe.)

In Sharpsky Client,

If i step out 32768 no movement occurs and position does not change.
If i step in 32768 no movement occurs and position does not change.

If i step out 32767 no movement occurs and position is set to 32,767.
If i step in 32767 movement occurs and position is set to zero.



It seems the movements outwards at 32767 are incremented by 32767 even if no movement occurs.

Im not sure if it was all these big movement testing causes it or just happening. but I got the PIC error again. It clears up after a bit, i think maybe its waiting to complete a large movement that doesnt actually cause a movement before it starts communicating again, as bringing up the ascom setup dialog and trying to set position to zero, asks you to wait for the motor to halt before setting position (even though its not moving and halt has been clicked)

[technofetishism]

Current imaging train takes ~97,000 steps to get to focus point, so the ability to be able to use the SGP GOTO position to go to 97,000 would be nice, Im not sure if this should be a SGP thing to just do multiple moves based on maximum single move.

[dtrewren]

Hi Nick,

Yep, I am getting the same behaviour above a total including backlash of 32767 .... ie (2^15)-1. The position offset interface is 16bits so I suspect there is a sign bit issue.

Crumbs, if you want ~97,000 steps then obviously 16bits is not going to be enough even unsigned. Leave it with me and I will look to extend the range.

Almost 2am here so probably not a good time to start.

Back soon & clear skies,

Dave

[dtrewren]

Hello Nick & everyone,

First up - Happy New year fellow imagers from down under ! Hope everyone had a fun time and there are not too many sore heads ?

I have been working on modifications to allow you to perform your monster focuser moves Nick. I'm happy that everything is completed and working well. Essentially I have made modifications in three areas as follows :

1. Modified the SharpSky driver to deal with a maximum focuser range of 150000 steps and a maximum single jump of 150000 steps

2. Modified the PIC firmware to deal with the extra step range by internally increasing the microprocessor dynamic range 16->24bits and also the USB message sizes.

3. Modified the SharpSky client to deal with the extra step range

The driver also has a new function which allows you to pre-set the displayed absolute position value to anything you like. So say you can zero the displayed position at some arbitrary physical position. The SharpSky client has a 'setup' tab added allowing the Properties dialogue pane to be opened at any time.

Ok, so here is what you need to do :

1. Download the bootloader PC application from the web-site and also the revised firmware (SharpSky.hex). The bootloader section is found at the very end of the web-site and there are instructions on how to re-flash the microprocessor over the USB. It's quite straight forward and only takes a few seconds to actually flash.

2. Uninstall the current driver being careful to make sure all ASCOM applications are shut down !

3. Download and install the new PC driver V3.11 from the web-site

4. Download the new SharpSky client if you use it V1.13

If you use the new driver with the old firmware things will still work just fine but the driver will warn you that you are using an out of date firmware version and then automatically reduce the maximum step value from 150000 to 30000. It will not warn you again once the reduction has been made.

I hope you get on ok with the changes, please let me know how it goes.

Cheers & clear skies,

Dave

[technofetishism]

Cheers dave, I'll test her out when i get home. :)

[technofetishism]

I cant see a link to the hex, is the file at http://dt-space.co.uk/SharpSky/source/SharpSky.hex te correct one?

[technofetishism]

Backlash compensation crashes SGP.

Set focuser position to 0, SharpSky driver returns this as -5 as position. SGP will crash if it gets a negative position.

[dtrewren]

Hi Nick,

Yes, that is the correct link. If I click on the link in your post I get the HEX file. To save the HEX file you need to right click the link and hit Save As ... and then put the HEX file somewhere locally.

:) oh I love software ! No matter how much testing gets done there is always something that slips through. I like the -5 position issue with SGP. I did most of the testing with MaxIm DL and set position to zero and up to 150000 to test. Clearly didn't perform the same test with SGP !

Luckily, that's a simple one to catch and fix - negative position :P

Have you managed to get the HEX file ok now ?

I will fix the issue with the negative position upsetting SGP later today, don't have SGP on my work machine.

Cheers,

Dave

[technofetishism]

yep dave, got the file on the focuser and all appears happy but that. :) bugs always get trhoguh, the nature of things. closed a mozzie in the scope earlier by accident :)

[dtrewren]

:) Mozzie in the scope sounds bad !

I should imagine your Aussie Mozzies resemble small birds to !

We have had sooo much rain here I think I am going to need a small boat of some description just to get to my gear at the moment !

I will post an update later to clear up the -position issue. That is a problem that has been lurking in the wings since day one I think. My client & I suspect MaxIm clearly trap -position. Although it only makes sense to transfer positive values the ASCOM API uses an type INT so it's perfectly possible to transfer negative values across the API ..... as you have just discovered. Whenever a new (to the driver) client comes along such as SGP there are always little oddities that need ironing out.

Will drop a post when fixed.

Cheers,

Dave

[dtrewren]

Hi Nick et al,

Ok, that little issue is cleared up :)

It is now not possible, via PC control, to move the position to a value larger than the Maximum value set in the driver or less than the Minimum set in the driver. This also applies to setting an initial position and hitting 'set position'

Notice it is possible to move the focuser past the driver limits using the manual hand control. I figured you might want to fine tune scope side without being blocked by the PC driver.

New driver V3.12 current on the web-site.

Cheers & clear skies,

Dave

[clive milne]

Hi Dave,
Rather than continue our recent correspondence on email, I feel inclined to make the following comments via the forum for the purpose of a broader (involvement in the) discussion:

The functionality of sharpsky would be enhanced by including a data (usb) and power distribution hub. It would be a fair guess that the majority of end users will have at least 1 item at the focal plane that would otherwise need to be routed away from the mount ie) CCD camera, focal plane rotator, guiding CCD... etc) all of which require cabling that is best avoided if at all possible.
Having USB ports available at the position of the OTA would also enable the end user to connect such things as humidity/temperature (dew point) sensors. From there it would be relatively straightforward to use a software based PID controller to drive PWM outputs for the optimum and efficient operation of fans & heater tapes.

Another idea that may be worth considering is a wireless dongle or cat5 connection for those that have their telescope located some distance away from their computer.

regards,
~c

[technofetishism]

Finally had a chance to test the latest driver Dave, can confirm that it will happily deal with numbers bigger than 16bit :) It'll get some more testing tonight as its finally cloud free :D

[dtrewren]

Morning guys (well up here it is),

Thanks for the FB Clive & Nick, much appreciated.

Hope you had a good imaging session Nick, I am more than slightly envious that you had a nice clear evening. Here in the UK we are currently stuck in a bit of a cold snap with a few inches of snow and freezing temperatures - typically the country has fallen to its knees and ground to a halt. Just for all you down under cooking in an Aussie summer and for fun attached is a picture of my back garden :)

Interesting comments Clive. The integrated USB hub concept has come up more than once and seems a popular idea. I have had a scout about and found suitable USB controller chips that would allow expansion of up to eight USB ports. Your comments have got me thinking so I'm going to wander off to my workshop with a pencil and have a think about what can be done.

So what we need is a focuser, dew control, USB hub & power source system. But I am thinking modular so you don't have to get the whole solution but just the parts you are interested in .....

Any input for anyone very gratefully received, always very interesting to hear what is really required !

Cheers & clear skies,

Dave

[allan gould]

Man up Dave and get out there imaging. That fat little devil with the carrot nose isn't complaining.

[dtrewren]

:) I don't mind the cold or the snow !

The issue is the horizon to horizon thick white cloud. Scope is out and running, but obviously not imaging - running some cold weather focuser tests just to make sure the electronics can deal with the cold & frost.

Would be nice to get some data at the same time ....

Clear skies,

Dave

[Karls48]

Hi Dave
Your focuser has been great, but unfortunately I will not be using my telescope for while. We are moving house. Big pain in the neck and lower down. As I was packing up telescopes and my little workshop I come across small-geared stepper motor with PCB, ULN2003 driver, header and four LED’s that I got some time ago from eBay for couple bucks and penny dropped. It should be fairly easy to modify your kit to drive two focusers. You already got buffered header to drive three or four LED’s (can not remember if it is 3 or 4 I did not connected it on my kit) so it would be to sacrifice LED indicators for second focuser motor. I may be talking complete rubbish as I’m out of electronic game for about ten years and only PIC’s I been using were OTP type.

[dtrewren]

Hi Karl et al,

There are multiple ways to skin the multiple focuser cat :)

The current SharpSky LED outputs are not suitable for driving a motor as the LEDs are driven directly from the PIC which can easily source 20mA per I/O. The motor is driven from the Darlington driver which is good for about 500mA continuous per output and is so good for motors with windings in excess of around 30ohms.

The good thing about PIC projects is the hardware is relatively simple. However, the detail then sits in the software both embedded code and driver code. Adding an extra motor ripples all the way up the software chain including the client. The standard ASCOM driver & API is only dimensioned for control of one focuser. There are two options to get around this. We could use a server to handle multiple focuser instances. Or we could generate two separate drivers, say main & guide scope . These two drivers look like two independent focusers to the client. We could then multiplex the two bidirectional command streams over one USB connection to a single piece of dual motor hardware but that means everyone has to pay for a two motor solution when the vast majority only want one. So the other option is to have a generic single motor controller that the user can configure as main or guide scope. So in the driver you tell the focuser hardware whether it is to be a main or guide controller and it is then configured with a unique USB identifier so the two controller can be addressed independently - I have tested this and it works well.

Crumbs, sorry about that got all carried away ..... :D

Cheers,

Dave

[dtrewren]

Hello fellow imagers,

I thought I would share the efforts of Alex from Bucharest. Alex ordered a SharpSky focuser kit from me at the end of last year and has been busy building & fabricating since. I was particularly impressed with the mechanical design of his telescope bracket. Alex has gone to some considerable effort but I think you will agree the result was worth the time invested.

Good job !

Cheers,

Dave

[peter_4059]

That's a neat design.

[MRL]

Dave:
I'm impressed with your focuser design, and am interested in building the kit - but I cannot figure out how to place an order. Please tell me how. I'm sure I'll feel silly after you tell me.
Very nice work by the way !
Mike

[rogerco]

I think you will find he is no longer doing the kits, I had the last one I think. I understand he is now going into commercial production. An excellent product, I am just finishing adapting it to my C8.

[dtrewren]

Hi Guys,

Roger is correct, I am not currently supplying the PCB based kit as have exhausted my supply of boards. Also correct is that I have developed a commercial version which now has a website :

SharpSky Pro website : www.sharpsky.net

It would be inappropriate to suggest sales through a forum, hence the current lack of sales information on the site. If you are interested in the commercial SharpSky Pro version please contact me via the email on the website : innovate@sharpsky.net

Cheers & clear skies,

Dave

[peter_4059]

Dave,

All the best with the commercial version of the product. I have never looked back since purchasing your kit - it has meant a giant leap forward for me in enjoyment and results from my gear.

Peter

[dtrewren]

Hi Peter,

Thank you for the encouragement :)

The commercial version has been a lot of work, I don't want to think of how many hours ..... I am surprised my key still fits the front door of the house and the wife is letting me in !

Yes I think you are absolutely correct - I found the same thing going to electronic focus. Once it is possible to focus remotely everything becomes at great deal more enjoyable and controllable.

I really appreciate everyone that took a leap of faith and bought a SharpSky kit - the level of interest was overwhelming and was the motivating factor in taking the project one step further to the commercial version.

Cheers & clear skies,

Dave

[wasyoungonce]

Hi IIS'ers

I contacted Dave about obtaining another Sharpsky kit (not the pro version) but he had sold all his stocks, but in lieu he sold me a pre-programmed 18F2550 PIC (many thanks to Dave) and I made up a PCB.

Well not quite made, I drew it up with eagle PCB and had the PCB made by OSH park (http://oshpark.com/). Layout is almost exact to Dave's but some minor changes like using Bussed SIL resistors (to +5V) instead of separate non bussed SIL for the LEDs, and some track changes. I kept the connectors the same, commonality is a must. Funny enough I found pre-made sealed mini DIN plugs on fleabay, mainly for old MACs and these cut-of work great for the encoder etc. I did make a small error with the position of the SIL LED connector...it's too close to it's SIL resistor pack and mount hole, but...it fits, at a small angle!;)

Result is...works very nicely tested fine! System is being put in the same original type case. A lot of work but well worth the effort, many thanks to Dave once again.

Attached are some images of Daves Sharpsky kit and my PCB.

edit: ahh just figured out a good fix for the Bussed SIL/6 PIN SIL space issue....put the bussed SIL resistor under the PCB! of course it's an interim fix, PCB design needs small design change but is usable atm.:ashamed:

[wasyoungonce]

Ok folks

I have a few spare Sharpsky PCBs (see post above) that are gathering dust and I contacted Dave, sharpky the designer with a thought of giving them away, free, but you have to buy a pre Programmed PIC for this, from Dave of course. Dave said he would supply the PICs at cost plus postage...cannot get better than that! I will send one PCB to Dave for him to peruse.

Thus I have another qty 2 to give away, essentially the same as the one here (http://www.dt-space.co.uk/SharpSky_Kit/) with small minor changes to the way I laid out the PCB tracks. Now, I can give away 1 complete PCB made up (with all parts and tested) for free for someone as I have enough parts left over for 1 complete (minus the PIC of course) unit.

The other PCB I can supply some parts like pre-made SIL male/female with fly leads and any required SIL resistors. I can also supply instructions and parts list etc for this.

What I am looking for is someone who has or wants to use stepper focusing preferably someone wanting to get into this. Would prefer to give the made up unit to someone who is not electronic conversant the other to someone who is. Obvious reason why.

Now the Shaprsky system is fully ASCOM compatible and uses same pin outs as robofocus or Moonlite but of course can be connected to work with any std small 12V unipolar stepper.

So who's up for this? Hands up!

[h0ughy]

would this work with a stepper motor to control a focus belt system for a lens and camera?

[wasyoungonce]

Yes it would as long at the stepper is unipolar (although you can get a bipolar to work on this, haven't tried, I believe)...even temp controlled with sensor and hand controller...wink wink.

Dave made a widefield rig I believe using the same sharpsky controller.

[mill]

Hi Brendan i am up for the build version and can pick it up from your place.

Cheers,
Martin.

[wasyoungonce]

Hi Martin yep done:thumbsup:...you have it, I'll have to make it up then PM you. I do this then test it with a PIC before giving it to you. You'll have to source a PIC from Dave but he is being very generous in his prices.

So folks, still another bare PCB to go incl some parts but you will have to source the others from fleabay, things like 4 &3pin DIN sockets.

[wasyoungonce]

Houghy, since you showed interest first, I wouldn't want you to miss out so.... ...if you talk nicely to me I might be convinced to make the other complete PCB up for you free as well!

Brendan

[mill]

Thank you very much Brendan :thumbsup:
Will make pictures when fitted to the ED80.

[h0ughy]

to be honest Brendan, i wouldn't do it justice as it would go in the cupboard until astrofest. there must be some deserving soul out there. thanks:thumbsup:

[wasyoungonce]

No problems David ...ladies and gents 1 PCB still spare with a few parts thrown in all free today!...as Robert Helpmann would say!

[torsion]

Hi Brendan, I would be interested in a bare bone system if it is still available. I have been looking into a stepper focuser, but haven't made the jump.

I will mount it on my C9.25HD, well need to start sourcing mechanical parts.

cheers,
Bram

[dtrewren]

Hello Brendan et al,

First off compliments to Brendan for taking the time to replicate the SharpSky
PCB and also for making the surpluss boards available. I am more than happy
to supply PIC devices for the boards at cost (part + postage) from the UK. Martin
has been in contact and I will get him off a programmed PIC on return from my
Christmas holiday.

Whoever, picks up the remaining boards please PM me and we can sort out
a programmed PIC to populate the respective boards.

Good job Brendan :)

Cheers & clear skies,

Dave

[dtrewren]

Further to the last post :

I meant to add the link to my Widefield rig as this was mentioned earier regarding
belt driven focusing ...

www.dt-space.co.uk/WF_project

Cheers,

Dave

[Astroman]

Oh dear, looks like I was too late... Terrific service Brendan and David, it's great to see.

[dtrewren]

Hi Andrew,

I think Brendan has three boards and offered one to me. However, I now use my SharpSky Pro gear (www.sharpsky.net) and although I appreciate the offer if someone else what's to take the last board and build it up that's fine with me and I will supply a programmed PIC device.

The destiny of the boards is obviously Brendan's call :)

Clear skies,

Dave

[wasyoungonce]

Ok Peter4059 and Bram scored a PCB each, 1st in 1st served, sorry Andrew!

Martian has the full assy but if you other 2 folks give me a little time I'll investigate getting some more DIN & USB sockets for the PCB and see if I can make them up for you.

What happened is I contacted Dave to see if I can get a Sharpsky kit, they were all gone but he sent me a programmed PIC and I reversed engineered his PCB and sent this to a PCB fab house. The PCB fab house makes QTY4 min and I only wanted one so 3 are extraneous to my needs and would otherwise be wasted.

However, I only ordered enough main parts for qty 2 ( I always order min 2 of each) so I don't have a full list of parts for the other 2PCBs but I'll see if I can get them and make them up as well...minus the PIC of course.

I've PM'd the winners and will post back soon. Many many thanks to Dave on all this, he's a champ!

Brendan

Edit:
ok just ordering the last parts for Peter and Bram, still need to order gray encoder and case will do that soon. Ordered 3 mini PIN sockets from fleabay, from a place I ordered before, they will get here soon but post is real hectic atm. Didn't want to order these from HK...had issues with that before.

So I'll do up Martians and for Peter and Bram...I'm collecting last parts and will have them done...hopefully soon.

Merry Xmas everyone!

[Astroman]

No worries Dave and Brendan, have to wait for the new scope anyway (fingers crossed in January when they become available)

Merry Xmas to you also Brendan.

[peter_4059]

Thanks Brendan - that is very generous of you. No rush - the summer clouds are setting in fast up here!

Merry Christmas.

Peter

[wasyoungonce]

Hi Peter many thanks, I have most parts I am scrounging thru my gear finding all sorts of things.

Martins is all finished bar the DC jack choice; encoder & temp sensor leads/case.

[torsion]

Hey Brendan, just PMed you. Thank you (and Dave) for your generosity.

Also, no rush plenty of other project going :)

cheers,
Bram

[dtrewren]

Hello all,

I have ordered up the required PICs so will program up and get them off on return from holiday.

Brendan .... if there are any bits you are missing let me know and I will pop them in the post. I have loads of the connectors up here top side as I use them on the SharpSky Pro gear and so buy in bulk.

Have a great Xmas everyone :)

Clear skies,

Dave

[wasyoungonce]

Thanks Dave I'm good atm. I just need to get some gray encoders. I'll do that tomorrow.

Brendan

[dtrewren]

No worries Brendan,

Anything you can't get just give me a shout.

Clear skies,

Dave

[torsion]

Hi Brendan,

What temperature sensors are used in SharpSky? There is one on the stepper (or connections within the 9-pin motor lead), and there is a possible separate one.

Can the second one be readout, but not used for focus temp compensation?

This is maybe more a question for Dave, instead.

Thanks,
cheers,
Bram

[torsion]

Also, what is the power requirement? How many amp does it needs? I guess that depends on the stepper, but is there a maximum? (the manual doesn't mention it :( )

I am trying to combine my power needs in a more convenient configuration, rather then having numerous mains cables and converts scattered around.

thanks,
Bram

[dtrewren]

Hi Bram,

I will answer your questions no problem :

The kit version of SharpSky only supports one temperature sensor. The sensor can be plugged directly into the PCB using a three pin mini-din or can be wired to the D-type connector. However, as I say only one sensor can be fitted the firmware will detect only one probe (the SharpSky Pro unit supports two separate independent sensors).

The sensor is a DS18B20 three wire type, the wiring instructions can be found on the SharpSky kit website : www.dt-space.co.uk/SharpSky_Kit

The build instruction PDF can be downloaded from the website and sections 11 & 12 detail the temperature probe connections.

Power wise the unit will not exceed 1A at 12V even if the motor is stalled.

Cheers & clear skies,

Dave

---------------------
SharpSky Innovations

[wasyoungonce]

Bam, I have a sealed DS18B20 sensor for you.

I was going to make them up to the 3pin DIN but if you want I can just send so you it to wire thru the motor DB9 and place as you wish. Or I can just give you a std non insulated DS18B20.

I have your PCBs all but made, just waiting for the gray encoder, DIN PCB sockets and few other small things.

I spoke you you about DC jack, aka you requested 2.1mm but I have not yet put that on so you can change your mind still!

Powering all devices is a real pain, I made a small distribution DC/USB hub so I can power multiple devices (and DSLR with +8V) and have a 4 port USB hub all in one. Things like this are invaluable to users and many users make their own.

[Astroman]

Like that board, was it your own design or a bunch of commercial bits thrown together?

[wasyoungonce]

Hi Andrew

just made my own except for the USB hub. I went down the route of doing my own hub but it was a real pain (although some tech/design docs are available on the net from USB hub IC designers), so I just grabbed a cheapie HUB and used a small TI +5V switchmode to power it. Aka it's a powered hub capable of 500mA per channel, via a rev polarity FET so Vbus would not back feed.

Same with +8V DSLR supply. The rest is just +12V distribution and ensuring centre pin size commonality for devices. Haven't we all faced this issue...2.1mm/2.5mm! I don't know how often I've been caught on this so I went on a quest to make all my DC pins sizes common.

I wanted it in a small package to fit between the dovetails. Works a treat can run USB/RS232 converter, DSLR USB, Autoguider USB; focuser USB... etc all at once.

But hey that's what hubs do....now need more ports!:eyepop::lol:

[Astroman]

Thanks Brendan for the info, got me thinking now :) Yes the 2.1/2.5mm plugs, boy what a pain..

[alistairsam]

shucks, missed out on this.

Brendan, I normally etch my own PCB's and have two spare boards with ammonium persulphate and toner transfer sheets. are you able to provide the pcb file if possible? I use designspark.
I'll check with Dave if I can buy a programmed PIC off him.
I do have a mclennan geared stepper as well.
I like that power and usb box of yours. nice work.

Cheers
Alistair

[wasyoungonce]

Hi Alistair, I don't see a problem sending the PCB files.....all the knowledge is in the firmware that is Dave's proprietary software.

If he will sell you a PIC I'll send you the files, but sorry in eagle PCB format but it's a damn small PCB and needs 2 layers and vias. If you use my design layout then I can give you the 2 commoned SIL resistor packs I used.

If I had the cash I'd be buying Daves Pro kit myself, but alas I have many other hands being outstretched at the moment!

[mill]

Hmm let me guess, Wife and kids???? :P

Anyone who wants very reliable connectors should buy these: http://www.jaycar.com.au/productView.asp?ID=PP2013&form=CAT2&SUBCATID=990#1
http://www.jaycar.com.au/productView.asp?ID=PS2014&form=CAT2&SUBCATID=990#1
They never come loose :P

I am not affiliated with this business in any way.

[torsion]

Hi Dave,

Thank you. One temp sensor will be exquisite, I was just thinking of using the second one to record my newly fabricated DSLR cooler box.

Re: power, 1A sound fine.

Does the PIC recognise where the sensor is plugged into? Or is that a software option? (just skimmed through the manual).




Hi Brendan,

Maybe sent the sealed temp sensor separate, thank you. I will most likely wire it through the D-type connector. Just wondering were to place the sensor for most effective focus temp compensation.

I like your USB/power hub, very nice.

Stick with the 2.1mm power plug, please (although I haven't made any head way with my power distribution). My latest idea is to have stereo sockets in be power box, and then the various leads with the stereo plug on one end and 2.1mm and 2.5mm (and 1mm? on the camera) plugs for the devices.

I have a few DC-DC converters (http://dx.com/p/lm2596-dc-dc-adjustable-step-down-module-green-227553), which will be powered by a 12V source. They will be tuned to 8V (camera) and 5V (usb hub), and I will have a few 12V straight through. I've never managed to reliably get my guide camera (QHY5L-ii, video mode) to work through the usb hub, so I am running a second usb cable. Come to think of it, with the focuser it will become a cable paradise ... maybe need to rethink again

Would the SharpSky play nice through a USB hub?

thanks,
Bram

[torsion]

Ah thanks. I was in jaycar the other day and didn't see them. Will have another look.
Bram

[wasyoungonce]

Hi Bram...yes my sharpsky works fine thru my USB (powered) hub. But not all hubs are equal especially non powered hubs!

The PIC recognises the sensor when present but temp compensation has to be selected in the settings for it to "compensate". I'll send the sensor separate to you as asked.

I am planning to run my temp sensor thru my DB9 to my ML motor and drill a hole in the motor housing so the sensor just sticks out, just a little. My motor housing will of course not be at the optics temp but the housing doesn't get hot and is pretty near ambient.

Dave implemented something like this already in his pro version.

[peter_4059]

Brendan/Bram,

The decision re temperature sensor wiring depends a lot on where you intend to mount the sharpsky. For my original unit I've got the controller in a box below the mount with the power supply and usb hubs. I just have a long cable running from the controller to the stepper. This way I end up with 4 cables running to the moving part of the mount - 2 USB (imaging and guide cam), 12V for imaging cam and stepper cable. I've always kept the imaging and guide cams on seperate USB's all the way back to the computer as DSI never liked playing with other devices. In my case I stick the temp sensor on the leg of the tripod.

[mill]

Peter,

The DSI is very power hungry (almost 500mA draw) and that makes it behave badly.

Dave,

Your inbox is full but my message follows below,

Thank you very much Dave and a happy new year to you and your family too :)
Whenever i need another stepper controller i will get one from you :thumbsup:

Regards,

Martin.

[wasyoungonce]

Hi Martin, Bram and Peter.

Bram and Peter... waiting for gray encoder, 2.1mm jacks and and 3 pin DIN sockets. Apart from that the PCBs are done except for above.

Martin I have yours all done & tested, just waiting for encoder! Sheee's what a to do! Fleabay is real slow this time of year.:sadeyes:

[mill]

Thank you Brendan, Dave has messaged me that the PIC is programmed and will be send tomorrow.
Some stuff from fleabay is fast and other stuff is slow :(
I will have some DS18S20 temp probes send from Maxim, so if you need some i will have them.

[peter_4059]

Yes Martin - I've also heard the DSI likes its power. Do you have power draw data for other guide cameras like the ZWO and Loadstar?

PS Brendan - thanks!

[mill]

Peter it is very weird because the lodestar is quoted as also drawing 500mA but it must be only when downloading a image.
I had a DSI once and it had to be on a separate usb connection or else it had some bad lines in the picture because of the power draw.
Looks like the DSI pulls 500mA most of the time and most modern camera's draw a lot less.

[torsion]

Thanks Brendan, great. I got an PM from Dave as well, so all good to go.

At the moment I am sourcing bits and pieces for my power distribution box. Managed to get all the connectors, initially got a tupperware box but had to put it back :) So back to finding a nice (cheap) box, probably will get one at jaycar ..

cheers,
Bram

[alistairsam]

Thanks Brendan

Dave has kindly agreed to send me a programmed pic.
Eagle format is fine, I'll stick to your design.


Thanks.
Alistair

[wasyoungonce]

Jeez Dave...still a demand for these! Maybe you need to go back into production and sales?

brendan

[wasyoungonce]

Ok update, DC 2.1mm Jacks (from China) and 3 pin DIN sockets (UK) arrived already mounted on PCB, just waiting for encoder and also some pre-crimped 2.54mm low profile plugs (for the LEDs) ....as this will same me time crimping my own as this is a real pita task with small gauge wire. If they don't arrive then I'll crimp my own but I dislike this task intensely!:lol:

Folks have said they would like to pay for my effort, but I have categorically stated "no" as this is not my design and only comes about from the goodness and willingness of Dave and some left over PCBs from me, so if you feel this way, maybe make a donation to IIS!

Shouldn't be long now, some things from China are real fast other come by camel train!:shrug:

[allan gould]

Well done Brendan. I really am amazed by Daves generosity (yours as well) and since I wanted another stepper motor controller I contacted Dave and purchased from him. Thought I could help pay for his efforts and I really like the unit he is selling at the moment.
Allan

[dtrewren]

Hi guys,

Apologies for not contributing, just got me some lovely solar imaging
gear so have been a bit distracted - only problem is ... no Sun :(

I did toy with the idea of re-starting the kit production but I think there
is simply not enough time for me to support the kit and the Pro version.
Putting the kits together actually takes quite a bit longer compared
to building the complete unit and sending out a tested board. However, I
found that the majority of guys actually wanted to build the board
themselves as opposed to the board being supplied ready built. I found
this especially true for astro guys in the Southern hemisphere who seem
more willing to get their hands dirty and have a go !

Send a bit of sun North .....

Clear skies,

Dave

[torsion]

Hi Brendan,

I saw your post earlier and wanted to reply with a photo of my (still almost) finished power distribution box. Unfortunately it is grant writing time so I haven't managed to get any time to finish it yet.

Anyway, your photos looking good!! Thanks heaps!

Also, Dave, just a thought maybe you can offer the PIC and empty PCB as a 'kit'. Because of Brendan's (and your) great generosity I don't have to shop and solder, otherwise it would have been on my radar sooner or later.

Cheers,
Bram

[mill]

I just received the programmed PIC from Dave :thanx:
A personal thanks to Dave and Brendan for doing this :thumbsup:

Martin.

[wasyoungonce]

i received the pre-crimped connectors, so was busy doing LED harnesses. Much easier this way.

Just waiting for encoders but your welcome to come over and see your baby work and maybe we can discuss the cud and maybe configure the system to you needs ....aka to fit in a AIO system.:thumbsup:

[dtrewren]

No worries Martin :)

That got to you quickly !

Dave

[mill]

Hi Dave,

Sometimes post is faster then pigeon :)

Picked the board up today from Brendan and put everything together.
I installed the Ascom driver but it doesn't connect :(
It worked at Brendan's place.
When i install the Ascom driver, it doesn't put any dll file in the "program files\common files\ascom" directory.
I did then try the ascom driver for the pro version and it installed a driver in the above directory but will not connect with the sharpsky, it will just say "cannot connect to sharpsky pro" (or something like that).
Brendan do you have the dll that you use and can you send it to me?
My email is martinmeup at dodo dot com dot au :thumbsup:

Martin.

[I.C.D]

G'Day Dave,
Will you control unit work with the JMI EV focuser ,I am at the present time using Shoe string between the focuser and the laptop.
Ian C :thumbsup:

[mill]

Ok panic is over :P
Intalled the ascom driver on another computer and took the dll and put it on the obs computer.
Voila! It connects now :)

[dtrewren]

Morning all from a very chilly UK :)

Excellent Martin, glad everything is up and running. I picked up your first post early this morning ans was scratching my head trying to figure out what might be the problem but sounds like you have figure it out and got everything up and running. Still not sure why the dll didn't install correctly though. Sounds like a privileges thing - what operating system are you running and 32 or 64 bit ? It maybe you need to execute the driver install as administrator - Windows 7 is really pedantic about who can do what and when :)

The SharpSky Pro driver will not work in any shape or form with the original kit design. The respective driver authenticate the hardware to prevent any mix ups and generate an appropriate message saying connection not possible.

Cheers & clear skies,

Dave

[dtrewren]

Hello Ian,

I have just had a look at the JMI EV focuser and it looks like it wouldn't be difficult to fit the motor. I have attached the focuser I think you have, is that correct ?

Cheers,

Dave

[mill]

I did install the Ascom driver with admin privileges and it is a 32 bit machine.
I only got a dos box and not an install screen as usual.
On the computer i used to get the dll, i got the proper install screen and not the dos box, it is just weird :screwy:

It will be clear the whole week as it looks like so it will be a nice test for the Sharpsky :thumbsup:
Thanks again Brendan and Dave :thanx:
Brendan i will bring the two motors tomorrow after work.

Cheers,
Martin.

[dtrewren]

Hi Martin,

Very strange that is a first ......

If you ever get a moment maybe you can have another go and grab
a screen shot ?

Cheers,

Dave

[mill]

I have to make it a video because it is a very fast dos box :)
Will do that tomorrow.

Martin.

[wasyoungonce]

Make mine strawberry! I like strawberry!:lol:

[torsion]

All very exciting. I have finished the distribution box and soldered up the various cables. Just working on a single 10-17 A power source ...

Brendan, I presumed that the 2.1mm power connector has the centre +12V, right? Just checking, believe it or not I have seen it the other way around. But if so, I can easily mod the cable.....

thanks,
Bram

[wasyoungonce]

Hi Bram

yes all power connectors are centre pin +ve...although you can bet sometimes someone will get it wrong or decide to swap them around in design!

I received the encoders today and will do some work on the system...it's a bit hot atm so I'll be trying to keep away from the soldering iron! Nearly all over..."bar the shouting!"

Interesting to see that Martins worked at my place fine but he experienced teething ASCOM issues on his set-up. I may be creating more headaches for Dave than he'd like!;)

Brendan

[torsion]

No worries, there is no rush. Enjoy the heat I guess..
Thanks,
Bram

[torsion]

Hi Dave, I received the PIC controller this morning. Thank you.

Now I will see to find a stepper motor. Is there an optimum 'focus travel' per step? That is system dependent I would say. Far away from focus it would be linear (sort of the aperture angle of the cone per step). Rambling on a bit, sorry. Will see to read up on it.

Thanks heaps.
Cheers,
Bram (from boiling Canberra)

[dtrewren]

Hi Bram et al,

Yes, there is a critical range for focus which is intimately dependent on your telescope optical speed, below is a table giving the critical depth of focus for scopes of various speeds.

So for example my Crayford on my solar scope was to hand and moves by 6mm with five turns of the 10:1 input control so ...

6000um / 5 = 1200um / revolution

SharpSky generates 2880 steps/revolution => 1200 / 2880 ~ 0.42um/step

The scope is about f/8 so that is 184 / 0.42 ~ 438 steps to cover the complete critical focus range of the scope - more than enough resolution to accurately nail focus.

Hope that's correct and makes sense ?

Clear skies,

Dave

Focal Ratio Depth of Focus
f/2 12 microns
f/3 26 microns
f/4 48 microns
f/5 72 microns
f/6 104 microns
f/7 141 microns
f/8 184 microns
f/9 233 microns
f/10 287 microns

[wasyoungonce]

Daves info is spot on but I'll add some. You can check out ccdcalc.exe (http://new-astronomy-ccdcalc.software.informer.com/1.5/)to find how various scopes and CCD combo's go together and part of the info given is Critical Focus Zone (CFZ) per combo.

As Dave said shorter FL scope have smaller CFZ...so you want lots of steps from your focuser in this zone...not too many as it will be verrrrry slow! Longer FL scopes...not so critical.

You can calculate various stepper combos on your focuser by Circumference C=πD (lets use D=5mm, the pinion for the drawtube diameter, for arbitrary sake, then each revolution of the pinion = 15.7mm movement). If I choose a stepper that has 2040 steps per revolution (one I used, has internal gearing) then I get each 2040C=π5 ~ .007699mm (~7.7 micron per step, 15.7/2040).

In a scope that needs CFZ = 20 microns then this is not good I'll need a stepper with more steps per revolution either thru smaller step angle or bigger gearing...or even a smaller DT pinion.

If you connect via a 10:1 reduction pinion drive then obviously you will get 10 times more step accuracy per step "point 7 microns" per step (depends on the pinion). This is probably just acceptable for this small CFZ. Given lets talk an F7.5 scope as an average scope then it's CFZ is ~123 microns so 7 microns per step is fine.

Anyway hope this helps, try not to choose a stepper that has too many steps per revolution as movement is slow...but more accurate.... Have a look around this may help you decide on choosing. No one can tell you how many steps you need in the CFZ...the more the better but too many and the focus movement rate is very very slow!

hope this helps.

[wasyoungonce]

Ok all done, tested running just like a store brought one..or two ..or three! Martian has his already.

Peter4059 and Bram I'll need you post address and emails ..by PM so I can send them, probably Monday, I need to sort packing etc.

I tested them all with my stepper system, all functions: Temp measure and compensation; manual control and manual control change; USB connection and connect via ASCOM ok; check all functions via computer; and Runs my ML stepper just fine.

I also did current draw checks and these were the same as original, spot on. So I'm happy to release them into the wild.

So, I'll send the: PCBs; PCB LED looms; cases; manual control and temp probes (both already made up). You will need to cut and drill and file the case for the PCB to fit in...honestly I am time short atm so I'll leave that part to you both but I'll send vai email a drill/cut CAD drawing with measurements on this.

I'll include all hardware necessary to secure the PCBs but as said leave the case cutting to you both. I'll also send some small mounting notes and details.

Finally...done!

[mill]

Also do not run any stepper with a current consumption over about 500/600mA.
The ULN chip is strong but will overheat and you will have to replace it (like me :P ).

[peter_4059]

Thanks for doing all that Brendan. Soldering the small bits is quite a challenge. I'm off to Bunnings to get a stepped drill so I don't stuff up the box.

Have pm'd you the address.

Cheers,

Peter

[torsion]

Thanks. Airy disks hey.



I have a Celestron 9.25", so will need to work out the pitch of the focus screw (should not be to hard). But I would say a factor 10x of 20x less then the critical focus zone should provide plenty of resolution.

Thank you both, it does help.
cheers,
Bram

[torsion]

Hi Brendan, Thank you!! That is mighty great.

i sent you a pm as well.

cheers,
Bram

[jwoody]

Hello all
Does anyone (or can you provide a link Dave) for the Ascom driver for the sharpsky kit focuser? I think the link on your website Dave is perhaps an old link for a old driver version (3.14)?
I have moved all my astro control software to a new pc.
Thanks
Jeremy

[wasyoungonce]

Hi Jeremy, not sure which version you are after, so:

The 1st version with PIC18F4550 is here. (http://www.dt-space.co.uk/SharpSky/)

The 2nd version, aka the shaprsky kit (PIC18F2550) is here (http://www.dt-space.co.uk/SharpSky_Kit/).

Client software is here (http://dt-space.co.uk/SharpSkyClient/).

Brendan

[wasyoungonce]

Kits sent out this morning, should get them soon gents.

Sent Alistair a small package of SIL resistors and SIL connectors.

So, all done! Good luck gents.

[torsion]

Thanks Brendan, looking forward to it (it currently is 'In transit' on Aus Post tracking).

Just about to sort out the motor and couplings onto my Edge HD.

cheers,
Bram

[alistairsam]

Hi,

I didn't really get the math, anyone able to do a quick calc for an F4?
As per Dave's data, the DoF is 48 microns. what resolution would I need with a geared stepper if i'm coupling to the main focuser shaft, not the 10:1 reduction shaft?
I'm using a moonlite and the reduction knob can't lift the load.

can a bipolar stepper be wired to work with this?

Cheers
Alistair

[mill]

Hi Alistair,

It has to be a unipolar motor 12V or for the old system 5V.
I am using the cheap stepper from Fleabay and it drives my GSO RC8 10:1 focusser with ease and i have it set very tight to hold a QHY9M with filter wheel and OAG.

[jwoody]

Thanks Brendan

I think the link on Dave's website for the sharpsky kit is to an old driver version (3.14), and for some reason that driver isn't working for me on my new astro laptop.
I think the newest version is 3.5 (as this version was on my old astro laptop) and it works fine. I am trying to get the 3.5 version to see if that gets my focuser working properly.
I thought my focuser may be broken but I hooked it up to my old astro lappy ( driver version 3.5) and it works fine.

I have no idea why the 3.14 version doesn't work on my new lappy so I am just trying to narrow the problem down.
Cheers
Jeremy

[Shiraz]

I had trouble too when I tried to upgrade - went back to the old version and everything working again. Also thought it might have broken - auugh - sure do rely on this thing :thumbsup:.

[wasyoungonce]

The load "not lifting" (slipping) sounds like the crayford pinion is slipping on the DT, needs tension/friction adjustment to fix this.

A ML pinion is ~ 4.75mm dia (well mine is) thus C=πD (D=4.75mm) thus each time you turn you pinion, 1 revolution, the DT will move the circumference of the pinion = 14.922 mm.

So you want to have a motor that moves this in small steps…a lot of small steps (aka a stepper motor) in a fashion that is finer than your finger can do and automatically!

So pick a stepper that has a lot of steps per revolution…the original Dave used is 2040 steps per revolution. Couple this to the pinion to move it. We know 1 full revolution = 14.922 mm now divide this by the number of steps = 14.922/2040 = .00731mm per step movement of the DT or 7.3 microns per step.

Your given CFZ for an F4 ~ 48 microns (ccdcalc states this as ~35 microns, so they are reasonably in agreement) 48/7.3 = 6.57 steps in the CFZ.

This is not enough, you need a stepper motor with more steps per revolution especially with filters etc.



Some people use reduction gearboxes like the McLennan gearbox (have I got that name right?) to achieve this, or use the 10:1 pinion or maybe even purchase a Hurst LSG35 stepper motor with a very high number steps per revolution.

http://www.hurst-motors.com/lsg35geared.html

If I was you I’d get the best stepper I could as you need high step resolution (or use a gearbox), maybe the Hurst LSG35012E98P, 14400 steps per revolution, 12V. This would give you 14.922/14400 = .00103 mm per step = 1 microns per step! Now we are talking! Thus CFZ 48/1 = 48 steps in CFZ for your system.

I cannot tell you how many steps in the CFZ you need but more is better and I suggest at least ~50 or more maybe 100 to give filter change step accuracy.

Lastly I think you’ll need a unipolar stepper…the Hurst and fleaby are mostly these types.

Anyone else want to chime in?

[alistairsam]

Thanks Brendan,

its clear now.
the reduction knob slipping is slippage at the reduction knob and not the main shaft.
it doesn't slip when I turn the main shaft. I've already increased the pressure and Ron also confirmed that that's why they couple the moonlite motors directly to the main shaft and not the reduction one.

I had a look at ebay and most geared steppers were 4096 steps/rev.

The moonlite steppers have a resolution of 2 micron.
with the awful seeing that I have, I'm not going to need that fine a resolution, but I'll see what I can fit.

Cheers
Alistair

Edit: just realized I also have this stepper and gearbox and whilst this is 125:1, it'll give me a resolution of 2 microns as the output shaft dia is 4mm, step angle is 7.5deg which should be enough and this is rated for 5V and a current draw of 550mA. sweet.
https://australia.rs-online.com/web/p/stepper-motors/3514647/

is it possible to run a 12v stepper with this circuit? if so, I also have a 250:1 gearbox but the matching motors are all 12v unipolar.
http://australia.rs-online.com/web/p/stepper-motors/3514574/ is a matching one for the gearbox.
sorry about the multiple edits

[wasyoungonce]

Alistair those motors look ok (except read below) and do have some nice gearing ratios...this is exactly what you want...a method to change gearing as you change scopes!

ML steppers are capable of "micro stepping", thus they can get down to 2 microns per step, this system cannot do micro stepping but that's not an issue with the right motor or gearing.

Just look at the specs for the motors as the stepper driver is capable of driving 500mA per coil but...this is de-rated for duty of cycle, thus probably at best 150mA~ 200mA per coil continuous operation. Ok the stepper isn't operating all the time but be aware of trying to drive coils that are too low in ohms, try to limit ~ 15~200mA per coil from motor selection.

I use Hurst which all appear to be ~ 65ohm per coil = 12/65 = 184mA per coil...this is sweet, no heating on package but I wouldn't go too much under this is coil resistance.

The 1st Mclennen motor is almost exact coil Rx as mine, the P542-M481U is a 5V system, sorry cannot use, but their pdf shows the P542-M482U, a 12V system...this is the one to get. Sadly doesn't show up on RS site!

These McLennen motors are listed (yes I know they are 5V just going into some more details on coil rx for the motors) is 52.2 ohms per coil and this is ~ 230mA...starting to get up a bit in current draw..."but"...since the system has a Schottky diode protection on the PCB, then available voltage is ~ 11.6V thus in reality is ~ 220mA per coil, and should ...mmm just make it ok as it's not being used all the time. Maybe a small heat-sink glued to the driver IC will help alleviate any concerns using these motors. you can also consider that a coil when being driven with current, heats the coils and their actual resistance rises ...meaning you should be ok at this I draw.

IMHO...go for the 12V McLennen system with different gear ratios...looks real nice indeed!

Hope this helps, sorry for the waffle !:D

[alistairsam]

ok thanks
i'll go with this one
http://australia.rs-online.com/web/p/stepper-motors/3514574/ and the 250:1 gearbox.
I'm guessing I won't need a heatsink?

so 1 micron resolution.
focusmax is going to have fun with the horrible seeing conditions from my place.

the issue is with shaft diameter of the stepper.
the 250:1 gearbox requires 2mm and 125:1 requires 3mm

Cheers
Alistair

[torsion]

Received mine earlier today, THANKS.

Had a quick look over, very impressed with the soldering. Nice job Brendan!

Haven't manage to get a motor yet, see if I can find one somewhere just to test it out :)

cheers,
Bram

[wasyoungonce]

Thanks Bram, just be careful inserting the PIC.

Soldering really is an art and unfortunately I'm at the low end of the art gene pool but have done more than enough to still do passable joints.

Most soldering these days from mass production is the non lead solder...which is really metal glue, not solder! Lead/tin solder 60/40 is still the best by far.

[peter_4059]

Mine arrived today also - thanks Brendan. I've got the PIC installed and will fire it all up for an inside test tonight.

[peter_4059]

Just fired it all up - works a treat - thanks Brendan and Dave.

[wasyoungonce]

:thumbsup:

good to hear enjoy!

[torsion]

All seems to work nicely - Thank you Brendan and Dave!!

Drilled the holes in the box and mounted it. Then I realised I forgot the holes for the leds .... so for now I don't have any leds (yet).

I found a stepper motor (unipolar, 12V, 48 steps), and manage to insert the leads into the 9-pin connector. I had to view the video-manual to workout the manual control button, which works like a treat by the way.

cheers,
Bram

[wasyoungonce]

Well done...you can squeeze the PCB out of the case by lifting the temp sensor and USB jack side of the PCB and tilt it up away from the DB9.

All very tight but it works.

Good to hear your making progress.

[alistairsam]

hi,

I finally finished assembling my controller, thanks to Dave and Brendan for their help.

I wanted to reduce the cables on my OTA so I did away with the 3pin DIN and mounted the temp sensor in the controller box and soldered it to the board directly. works fine for my setup.

I also found a 2.5mm male to 2.1mm female DC power socket adaptor. this allows you to use the standard 2.1mm power adaptors if the socket is 2.5mm.

I still need to tweak the step period setting for my moonlite stepper, but I did have a few questions,

1. if you set the step period via the software, does the pic store the value and use it with the manual control? mine has a bit of a lag with the manual control and it doesnt recognize the pulses if rotate the knob too fast.
I will add two spst micro switches next to the encoder so I can use them instead of turning the dial. just a personal preference.

2. how is the temp compensation intended to work between subs?
I use maxim and ccd autopilot so will be refocusing between filters, but if I'm taking say 10x15 min subs for the same filter and the temp drops, will it adjust the motor during the sub exposure? is it independent of maxim or focusmax's control?

anyone using the moonlite 2.5inch newt focuser with the stepper? if so, could you post what step period works best with it?
I've tried between 4 and 35. 4 is the fastest without jitter, 10 was suggested by Dave and is smooth. gets progressively slower and at 35, there is no movement at all.
mine is an F4, so I will need the smallest mechanical step possible with the moonlite stepper.

Brendan, your PCB layout is very good, thanks for letting me use it and thanks again to Dave for the PIC.

Cheers
Alistair

[dtrewren]

Hello Alistair,

Good job, looks great - I can answer your questions :

If you set the step period in software it is stored in the controller (EEPROM). This value is applied to both manual and PC based control inputs. The manual control was intended for fine tuning the focus rather than large movements. Therefore, if the manual control is spun faster than the software debounce period input will be lost.

When temperature compensation occurs is generally a function of the client software rather than the focuser driver. The focuser driver has no knowledge of what the camera is doing and so the client enables/disables temperature compensation (or should) when subs are being taken. So when I sub is underway temperature compensation should be disabled.

Just to clarify, the step period does not change the physical step size delivered by the motor but instead the length of time energy is delivered to the motor. The physical step size of the motor is a function of the motor design and the attached gearbox. The 35BYJ motor delivers 2048 steps per revolution and this is fixed with the current firmware design. As you change the step period the motor will speed up or slow down but the number of steps per revolution stays the same. Each motor will tend to have a sweet spot where speed and torque are optimum.

Hope this helps ?

Cheers & clear skies (raining here as usual),

Dave

[dtrewren]

Good afternoon guys,

Ok, I have made a few modifications to the SharpSky firmware. To be honest one of these changes should already have been in but somehow slipped through the revision net. I have enhanced the way the temperature probe is being read by the PIC micro to make the read less invasive. The current V4.0 has an issue whereby reading of the temperature sensor interrupts the motor move (this should have been fixed). Also the sensor read was disturbing the operation of the manual control.

The new V4.1 firmware load fixes the motor interruption issue and makes the manual control much more responsive.

The new firmware is now available on the SharpSky kit website :
www.dt-space.co.uk/SharpSky_Kit

Also for those that have built a focuser using a development card and a PIC18F4550 device a new firmware image is available on the original website :
www.dt-space.co.uk/SharpSky

Quick reflash instructions :

- Download the PC bootloader from the website
- Download the new firmware load (right click and save as)
- Run the bootloader PC application
- Push the manual control button & while pushed power up SharpSky. The bootloader will see the PIC and respond
- From the bootloader Pick the new firmware HEX file you have saved in the second step.
- Program & verify
- Reset device

Good to go you are now running V4.1 and this will be displayed in the ASCOM setup page for the driver.

Any questions or problems with the reflash please fire at will :)

Cheers & clear skies,

Dave

[wasyoungonce]

Hi Dave & other Sharpsky users...just finished a kit for netwolf (Fahim), Alistair made his own. Alistair supplied the parts I just the goon who slap it together.

One thing ...I noticed Alistair sent me a 3 pin pre-moulded mini DIN lead (http://australia.rs-online.com/web/p/din-cable-assemblies/0463489/?searchTerm=3-way+Male+moulded+plug&relevancy-data=636F3D3226696E3D4931384E446566 61756C74266C753D656E266D6D3D6D61746 368616C6C7061727469616C26706D3D5E5B 5C707B4C7D5C707B4E647D5C707B5A737D2 D2C2F255C2E5D2B2426706F3D3926736E3D 592673743D4B4559574F52445F4D554C544 95F414C5048415F4E554D45524943267363 3D592677633D4E4F4E45267573743D332D7 76179204D616C65206D6F756C6465642070 6C756726). This a real good idea in that the 3 PIN Mini DIN plugs I had been using were pretty poor quality and didn't fit well due to the backshell case diameter. Also had a few suffer from "pushed pins" and had to toss them. This pre-moulded lead is much neater/smaller.

But, you need to splice the pre-moulded lead to the sensor. Well I did that buy slitting the lead open and stagger splicing and heatshrink, right up near the head of the sensor and covered it back up with the original outer layer and heatshrink up to the probe. The result was ok, better than before.

However, I did see guys over at Homebrewtalk (http://www.homebrewtalk.com/f51/make-your-own-precision-ss-temperature-probe-101192/)forum using DS18B20's and stainless steel caps (http://www.brewershardware.com/Straight-Tubes/) and making their own sealed sensors. Which I though would suit these pre-moulded leads real nice. Obviously they use a plain non-sealed DS18B20 and heatshrink over the legs and pot the device into the cap. I was thinking JB weld...it's non conductive electrically and should be thermally conductive.

Anyway just regurgitating this idea. Other may learn from my trials.:shrug:

[netwolf]

Thanks Alistair Brendan looking forward to this unit. Appreciate your efforts in getting this built for me can't wait to try it out. I just need to now work out the motor And mounting side of this.

[alistairsam]

Hi Dave,

Tried to send you a PM but your inbox is full.
I can confirm that the firmware ver4.1 has fixed the pauses and the manual control is a bit more responsive.
I will add two micro switches in parallel to the encoder though. not sure if it'll work. would that cause issues with too many interrupts raised to the PIC?

I was testing CCD Autopilot with focusmax and the sharpsky ascom driver and couldn't get the temperature reading. maybe its because focusmax isn't passing that through since you can't choose the ascom focus driver from ccdap direct.
CCDAP does temperature compensation so it applies corrections between subs and can refocus between filters, after a meridian flip and so on.
I will do some tests and post results.

Cheers
Alistair

[wasyoungonce]

Hi Dave..Just flashed my 2 controllers with ver 4.1 and noticed they appear more responsive, many thanks. Noticed that the new firmware revision number is not immediately displayed when you open "client.exe, properties". Still listed as ver 4.0. Then once I connect it changes to ver 4.1 so not a biggie, just mentioning this for others as I initially thought, "hey the flash failed"?

Also noticed that I got a firmware flash verify fail using an older bootloader? No matter downloading and using the latest works ok.

Keep up the great work:thumbsup:

Brendan

[dtrewren]

Hi Alistair, Brendan et al,

Good stuff !

Alistair I sent a PM regarding CCD autopilot now I have purged my inbox, SharpSky stuff had filled it up :)

I connected CCD autopilot to SharpSky via FocusMax and it appears to read the temperature once on connect but then fails to update even though FocusMax is reporting temperature changes about once a second. Not completely clear to me how CCD is supposed to function in this area. Tried changing various settings but CCD is not picking up temperature changes from FoxusMax no matter what I change ? I will have another play later.

You shouldn't have a problem with the switches although I have not tried stand alone switches - let me know how you get on.

Hi Brendan,
The version number will not update until you connect, it is only at this point that any information is exchanged between the driver and controller. So as you say once you connect and open the setup window the new version V4.1 will be displayed and refreshed every time you connect.

I have upgraded the bootloader application on the website to V1.2 (this was an oversight and should have been done before). The flashing did work despite the error. The error was only a verification error due to a modification I made to some securing data in the bootloader.

You should now notice (with V4.1) smoother motor movement with no pausing and a much more responsive manual control. Also the heatbeat LED used to tend to pause sometimes during a temperature read - this is also now fixed and the LED flash is steady.

Cheers & clear skies (not here) :( ,

Dave

[alistairsam]

Hi Dave, Brendan,

I had an issue last night where the controller doesn't have the status led flashing anymore and I cant connect.not sure if its completely dead. I checked input voltage, its 12.1

Any suggestions on troubleshooting, voltages on pins of the pic etc?

Thanks
Alistair

[Garbz]

I'm not sure entirely on what schematic you're using. Brendan showed me one recently but if it's the same there's a few things you could check:

On the DB9 connector for the motor:
Pin 5 - 12V - This would rule out problems with the internal power connection.
Pin 7 - 5V - This would rule out problems with the internal regulator.

Pin 9 is ground. Take care not to short between any of the pins as it doesn't look like the power supply has any decent short circuit protection.

[dtrewren]

Hello Alistair,

Sorry to hear you are having an issue. As has been suggested check the power rails to see if the PIC is getting juice. The design does have reverse polarity protection but not short circuit protection. A DB9 connector generally ensures against pin shorting.

If you do have power the only other thing that can halt the PIC (assuming it is not damaged) is a problem with the crystal or associated capacitors. Power the board on while depressing the manual control button - this will put the PIC into boot mode and the manual control LED should rapid flash. If this does not happen that suggests the PIC has no power or the clock is not running. If the LED does rapid flash the PIC is alive and well but for some reason the application code has become corrupted. This is not likely but is possible so you could download the .HEX file from my website and reflash the PIC.

Report back and let us know how you get on.

Cheers,

Dave

[alistairsam]

Thanks Dave, Chris,

Very strange, it actually worked today.
I had it setup at home yesterday, didn't work. I did measure voltage in the power input connector.
I packed up and setup tonight at a dark site, it just worked.
not sure if it was the dew or cold as its right on top of my scope, but i will save the troubleshooting tips if it happens again.

Dave, do you have a link for the temp compensation section, I'm not clear on how to log changes through the night and use it when connected via Maxim.
I'm not using focusmax at the moment.

Thanks
Alistair

[dtrewren]

Hello Alistair,

It is a little tricky to say for sure but my hunch would be condensation around
the crystal and tank circuit. The crystal has 33pF caps hanging off it and it wouldn't
take much condensation to stop the crystal or pull it off frequency. Pulling it off
frequency wouldn't kill the heart beat LED but might kill the USB comms. The 4MHz
from the crystal is input to a PLL with a 96MHz ouput, then a /2 post scale to 48MHz
which forms to base clock for the USB module. If the 4MHz is off frequency or has
significant phase noise the PLL may not lock as required.

I am currently on holiday in Venice, will be back in a few days and will get back to you
in more detail regarding the temp compensation. The basic idea is you log the temperature versus position over a nights session while focusing manually at
intervals. This data allows you to work out the coefficent of expansion of the scope
in units of steps/degree. The expansion coefficent is then input to your software of
choice to perform compensation automatically.

Cheers,

Dave

[wasyoungonce]

Alistair...did you conformal coat the PCB (http://www.jaycar.com.au/productView.asp?ID=NA1002)?

I coated the bottom with spray and used touch-up brush around the top coating all exposed component legs etc.

Just good practice to do so. Oh don't get it in your connectors and just check your DC socket and jack have the same sized centre pins. That said...I have seen a new range of DC jacks that can accept 2.1 and 2.5mm centre pin DC plugs...nice!

Dave...Venice....oh some people have all the luck slumming it!;)