ASCOM and Arduino

[tekkydave]

I have an electronic focuser I built myself using an Arduino Nano & a stepper motor. It's pretty basic and control is just via a 5-way switch to control clockwise/anticlockwise at fast/slow speeds and a rotary encoder to give fine adjustment. This is all working and fine but I would like to control the Arduino from APT as I plan to control my scope remotely from indoors in order to have a go at AP. I already have the ASCOM platform and Celestron Driver installed in order to control the scope from APT but I'm not sure what I need to allow APT to 'talk' to the Arduino using ASCOM.

Any help & advice would be welcomed. I don't really want to have to write a new ASCOM driver if one exists I can use and I normally program using Java.

Thanks & clear skies.

[tekkydave]

Here's a photo of my focuser. The switch on the top of the controller has 5 positions (I think these are intended for use with guitars originally):

Full Left = Fast Clockwise

Half Left = Slow Clockwise

Centre = Stop

Half Right = Slow Anti-clockwise

Full Right = Fast Anti-clockwise

Also:

If the switch is left in the Full Left/Right position for 8 seconds the speed doubles - this is useful for large focus adjustments.

When the switch is in the Centre position the knob on the front, which is attached to a rotary decoder gives fine focus adjustment.

The motor box contains an Arduino Nano, a standard 5V stepper Motor + driver board and a 9V battery (PP3 type).

The toothed belt fits over the focus knob on my 127MAK and the motor box is secured in place by a leather belt strapped around it and the scope tube.

I had great fun building this last year and it was my first Arduino project. I've used it a few times and it certainly reduces the shake introduced when moving the focus knob.

I would like to be able to connect it to the laptop running APT which is controlling the scope and Canon 1100D. This would enable me to control everything from inside in the warm. The Nano's USB port is accessible on the other side of the motor box. I can make the necessary changes to the control program to read its instructions from there rather than polling the switch & rotary decoder.

Sounds simple but I suspect it isn't.

[Chris Rowland]

The "Introduction to Developing an ASCOM driver" pdf in the ASCOM Platform developer documentation has a worked example of a focuser driver.  It has a suggested control protocol that's easy to implement in an Arduino.

You may be able to make a driver of your own by doing little more than generating a driver from the ASCOM Templates and copying and pasting the control code from the pdf.

Visual Studio Express is available as a free download.

Chris

[tekkydave]

Thanks Chris. If it's that simple I might have a go. I have a copy of VS and I've done some C# in the past.

I was sort of hoping there might be an ascom <--> arduino standard driver floating about.

[Chris Rowland]

Let me know how you get on, I wrote the guide I'm promoting and did my best to make it clear, but it's difficult to get this right as I've been at this for some time and can miss the things that will trip beginners.

Chris

[kookoo_gr]

there is a video tutorial

for developing an ascom driver. please note that the video does not play on your browser (i have firefox) but if you download it with download helper at firefox it works perfectly

edit: welp it works perfectly here to watch.

[tekkydave]

Thanks guys. I have VS2010 up & running and the Ascom Dev package installed. Hopefully I'll get some time this coming weekend to build a basic example.

[blinky]

There is a group on Yahoo - who have created all the software to drive an Arduino focuser, they also have an Ascom driver as well. Just google 'yahoo focuser group' (Last time I mentioned the name of the group, it caused erm.... problems!).

I am using the software/ascom driver and it works fine with FocusMax

[tekkydave]

Thanks. I'll take a look.

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