Generic ASCOM serial port driver?

[wobblewing]

Hi all,

Further to my DIY EQ platform (thread here )....

 

I've got some experience using this now and have managed some reasonably decent tracked DSO images with the 150p dobsonian.

I'm now working on a few mods.  Namely an addition of a Declination trim adjustment by tipping the 'scope, but also a serial interface so I can potentially add guiding to the mix.

Since I can create full serial control via a COM port profile over USB (easy with a micro:bit), what I'd like is a generic ASCOM driver which squirts pulse positioning string out to the serial port, thereby allowing the EQ platform to be controlled by software such as APT.

Does anyone know if such a driver exists.  Of course, it may be possible just to grab a skywatcher (or any) driver, but it would be easier if a very basic one has already been written with the serial commands documented (since commercial drivers will not be documented).  All it needs is something like RA+, RA-, DEC+, DEC- control over serial..

Anyone know of one?  I've done a bit of searching, but get lost in ASCOM documentation without it leading me to a useful generic and basic serial driver....

Thanks!

Andy

Edited December 27, 2021 by wobblewing

[malc-c]

Andy, not read your other thread, but would it not be simpler to try and customise EQMOD or GSServer as the ASCOM compliant driver to handle communications between software and the mount ?  As both are open source the documentation may be handy in developing your own driver ?

[wobblewing]

I'll have a look at that, Thanks Malcom.

I'm not much of a Software developer, so was hoping to grab something that I could find on github somewhere and then write the mount end code to match the commands in the driver! 🙂

 

Edited December 28, 2021 by wobblewing

[malc-c]

Andy, I must admit most of your build thread went right over my head, but my thoughts on control are "why reinvent the wheel".  There are two / three existing protocols used by manufactures such as Skywatcher, Celestron and Meade.  These already handle the instruction set that their corresponding motor controller firmware understands.  I'm no expert, and there are those on here that are far more knowledgeable than I, but as far as I know, drivers such as EQMOD or GSServer will receive the "I want to goto this location" message from the planetarium software, and then tag on the "slew to these" instructions to the co-ordinates and send it to the firmware running on the motor board.  The firmware then does the maths based on the parameters (worm gear teeth and ratios etc) programmed into it, so it can sent the required number of steps to each motor.  Now your mount is not your standard EQ mount, so maybe EQMOD and / or GSServer command set won't work in your case, but it may give you some catalyst to develop your own protocols etc.

skywatcher_motor_controller_command_set (5).pdfsynscanserialcommunicationprotocol_version33 (4).pdf 

here's the protocol and command set for SW mounts

EQMOD page http://eq-mod.sourceforge.net/introindex.html

Hope that helps

[wobblewing]

Yes, that's exactly my point... Just looking for something simple that is 'pre-done' but has enough documentation so I know which serial commands they send out, so I can make my mount respond to those commands.

Then it's easy.. I shouldn't really need to develop a driver at all.

Maybe those documents you've posted tell me these commands... I'll check those out - many thanks for those... Where did you get them from?

My platform already takes out the sidereal rotation.. my intention is to say calibrate its position in RA/DEC in APT and then just do the final bit of positional trimming (and later, guiding) just using simple pulse commands similar to ST4 (e.g. back a bit, up a bit etc).  In essence, ST4 is all that is required, but I'd like to have a little more control through APT or EQMOD etc.

I also see that someone has done something with an arduino as a serial to ST4 adapter.. The guy wrote a driver for it.. maybe I could use this: https://hackaday.io/project/4386-arduino-st4-telescope-control

 

Cheers

Andy

 

Edited December 28, 2021 by wobblewing

[malc-c]

Andy, the protocol documents can be found on Skywatchers own website, I just attached them for convenience.

If you are looking at ST4 as a mean of crude control, then there are already USB > ST4 adapters for around £55 - FLO sell them here 

The ST4 "standard" has been around since the late 70's and the web is full of home made adapters using traditional transistors and opto isolators, through to arduino nano's.

I'm afraid I can't offer any further help as I don't really know how to get the SW protocol decoded by the SW firmware so that the mount tracks sidereal - It might be worth posting on the EQMOD IO group, as Chris and a few of the developers should be able to help you out with that. 

[wobblewing]

Thanks Malcolm.  The drivers for that little gadget from FLO may just be the ticket!

(sorry for the late reply!)

Edited January 6, 2022 by wobblewing

[Chriske]

Andy,

Are you any closer to a solution...?
Tipping a Dob on a eq Platform during imaging will only work when you're busy working at culmination point.
But correcting while at more East or West position will not work at all. You will be tipping toward the zenith and not to(ar away) from Polaris.