USB stepper control for a Newt

[uspl]

Hi all,

I have been playing with this USB stepper controller (http://www.ar.com.au/~softmark/page44.html) and have it running nicely driving three steppers at once. Rather than just making Mecano move for the lids I thought I would try it on my scope but am strugling to find suitable software. Scope.exe would seemt he logical starting point and I found talk of Scope II (java) but cannot find the actual software.

The card uses a custom OCX to allow programming via VB and can generate microstep and half step sequences, my issue is getting something other than my poor VB programs to talk to it.

If anyone can help with this it would be most appreciated.

[davidpretorius]

aaaaaaaahhhhhhh, the memories are flooding back.

i have this same unit and have manage to blow the chips a few times (stupidity on my part not warranty).

I started down this track and was going to get my pc to run the steppers, one for ALT, one for AZ and one for focussing.
I looked at the MATHS and even wrote some a WIndows application that did the conversions to track in ALT/AZ mode etc

Instead of completing the project I ended up buying the DOb driver II 2nd hand, the coding had been done, the stainless steel knurls, housing etc were all part of the unit............. a lot of cost and development time saved from my point of view

Instead i will eventually use the Stepper motors and controller to drive the collimation screws on the bottom of the scope ie integration into the primary mirror cooling unit.

[netwolf]

Dave i remember all those threads.

Uspl, Scope II is has to be purchased, and i am not sure it will work as it is written for controlling the Servo systems.

If your doing it low budget then i would look ad the Roboscope yahoo groups. They are using a Austostar 497 controller with motors from Meade DS mount or better yet the LXD mounts. This method is a very good one because you will have a proven and tested hand controller that just works and is easy to use.

If your looking for a simple tracking solution then you could possibly write your own Alt/Az tracking only application or perhaps borrow from Dave's code. This would be a good solution for simple point and track mode, and you could add some encoders and Davek's DSC system to give you a push to point and track system.

Another option is to consider a PIC or similar design with code for tracking only with some buttons to provide different tracking rates.

And here is another one you could look at http://martin-cibulski.de/atm/mount_...er_4/index.php




Regards
Fahim

[uspl]

Thanks for the advice guys, I am doing this purely for fun and as a challenge. I am going to attempt my own tracking app rather than a total GOTO style, I will post my results here if I have any luck

Regards

[Barrykgerdes]

Hi

About 10 years ago I wrote a couple of programs in Qbasic and compiled them so they run in a DOS window (or command line). One of them was to drive a Dob11 Driver and another just two stepper motors. The programs were for driving my old 8" Dobsonian. They are complete with alignment stars, planet calculator, Messier and NGC/IC catalogues. There is also a two star alignment routine. I still have the programs and a test box coupled to two stepper motors salvaged from old hard drives. It runs from the printer port.

The source code (Qbasic) is available which could be used (if you can read basic) to salvage the algorithms necessary to write a similar program in any language.

Barry

[uspl]

Thank Barry, if you can release some of the code for me to look at I would be grateful.


It is 19:20 AEDT and there is news.
In the imortal words of Marty Feldman, "it lives, master"


As I sit in my slowly darkening shed, a glass of Dan Murphy 2008 by my side, there is hope !!

X, Y & Z axis all tracking and the vb.net timer call giving me a perfect 15 degrees per hour on the Y axis, or at least as perfect as I can measure it.

Tomorrow the real engineering begins with a trial run on mounting to the scope.


Stand by

Regards

[netwolf]

Well done uspl, sounds like your making progress.
I was lucky to have a chance to sit down with Barry and see some of the programs he has written. Some very good algorithms there, might be just the thing you need.

Regards
Fahim

[Barrykgerdes]

Originally Posted by uspl

Thank Barry, if you can release some of the code for me to look at I would be grateful.
Regards

Hi
I will attach a zip file containing the QBasic source code for the DOB2 driver and a stepper drive program. Each program has two parts (64k limit for basic). The first part *Drv.bas calls a location data file which I think will be generated if it isn't present and generates a planet and comet table. The second *Drw.bas uses this data along with the star and NGC cataloges (not included) to do the actual driving. Both are reasonably REM'd to assist in reading and in ASCII of course. I have compiled versions of these programs as well.

[davidpretorius]

Thanks Barry, i will have a look through with Interest

[uspl]

Nice one Barry !!

Now I can see why your observatory is so impressive; anyone who takes the time to cut code for planetray perturbations in a hand written application is WAY over anything I would aspire to.

Thank you for the algorithims; they will be very useful and save heaps of time when it comes to doing the co-ordinate mapping (assuming I ever get the motors to play nicely with the mount)

Regards

[Barrykgerdes]

Hi uspl

I didn't do anything spectacular. I just adapted the basic from Peter Duffet Smith's book to suit my own needs. Those programs only took about 3 months to get running and about 3 years of refinements. The basic idea was the same as your requirements.

I wanted a way to automate a 8" Dobsonian in the days before goto telescopes. I got a dob11 driver and adapted it to the mount. The mount was first modified to have ball races in the altitude supports. Then I worked on the azimuth to make it roll on ball races with a proper spindle. There are full details on the mount mods on my web site.

Initially when controlled by a computer 386's were the best chips running at about 33 Mhz. This required a couple of tricks to get the processing fast enough. Also the DOB11 needed to be driven sequentially alt/azm and this was done once per second from the computer clock. the result was a zigzag movement when tracking at high resolution. I got around this by making a synthesized .1 second clock from the timer xtal. This did not work too well because the computer was too slow. When I got a 486 66Mhz computer it worked well.

At this stage there was no alignment routine. This took some time to get coded. Basically you take a guess at the scopes attitude and do a systematic fit till the error gets to zero. Normally about 5 refinements gets the error down. There is also a document on my web site explaining the procedure.

There was a bit of slippage on the azimuth drive so I designed a belt drive for it but never got around to implementing it.

I never really used the telescope after I got the system to work because by this time I had bought a LX200 10" scope and I gave the old dob to my daughter. She just uses the Dob 11 in its standard non computer driven form.

Barry