Adding Custom ASCOM Driver for RaspberryPi + Cam Connection

[Dominik Laa]

Hello !

I really like openPHD - it seems like a real good basic software. What I don't like about it is that you can't connect your hardware over network. The same thing seems to be possible with indi (another open source software). I have already checked indi but they have no usefull support for the raspberry pi camera (they use the v4l2 driver which basically limits the exposure time). 

I'm also a C# developer and thought that I could develop ASCOM driver which streams the images that are used for guiding to my pc. And than send again the correction commands to my mount (that is also connected to the raspberrypi). 

And thats actually my plan but there are a few questions:

1. With my current setup the RPI Camera V2 NoIR Module needs 3-6seconds to get vissible images of stars - is that okay or do I need to change the setup ? 
2. I'm using a 70-300mm Nikor lense for the RPI Camera and a 500mm muskatov mirrow-lense on an APS-C camera
3. Tests have shown a maginfication factor of 6 -10 times (caused by the smaller webcam image sensor - may be very good for planetary shoots)
4. And here comes the main question: I'm able to progam and build drivers but how do I get OpenPHD to actually use my self developed ASCOM drivers for the guiding camera / mount ?

Hope someone of you has ideas about this project.

Thanks in advance,

Dominik

[Andy Galasso]

On Sun, Mar 19, 2017 at 6:26 PM, Dominik Laa <domin...@gmail.com> wrote:

1. With my current setup the RPI Camera V2 NoIR Module needs 3-6seconds to get vissible images of stars - is that okay or do I need to change the setup ? 

The answer depends on the quality of your mount's RA tracking.  If you wait 6 seconds between corrections, then your mount's tracking error over the course of 6 seconds needs to be within your margin for what error is tolerable for your imaging.

Try running the guiding assistant for at least one full worm cycle. That will show you how smooth your RA tracking is without guiding so you can evaluate whether 6 seconds will be ok.  If you are not sure how to interpret the results, please post your Guide Log and we can help.

BTW, if the limiting factor is image download time, you can use subframes to greatly limit the amount of data transferred from the camera (assuming your ASCOM driver implements the subframe capability on the RPi side.)

1. And here comes the main question: I'm able to progam and build drivers but how do I get OpenPHD to actually use my self developed ASCOM drivers for the guiding camera / mount ?
   

PHD2 detects all of your installed mount and camera ASCOM drivers. They show up automatically in the mount and camera drop-down lists in the connect equipment window.

Andy

[Dominik Laa]

I can't tell about the quality of my mound because I want to build it on my one and before doing that I need the software to run.

Maybe I will get my self a 50mm 1.8f used Lense - that may be lot better when it comes to exposure time. But it may be the lower limit for my 500mm (x1.5) mirrow lense. But first I need the software running before spending more money on that.

I also managed to install my self build dummy (empty) driver.

Thanks !

[Hans]

Do you intend to run PHD2 on the RPI or on a remote machine ?
If remote then you cannot use ASCOM afaik. Which leaves INDI as an option and for this there's two things that need to be done.
Given ASCOM I assume your remote machine is MSWindows, so then ticket https://github.com/OpenPHDGuiding/phd2/issues/450 needs to be implemented, and you need an INDI device driver for the local camera that can use it with exposures up to 6 seconds (not sure if this driver already exists).
-- Hans