From: "ChrisB" <chboss@hispeed.ch>

Date: August 15, 2011 5:36:58 AM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: Guiding HW Addition

Good idea Milton, would love to hear about your progress.

regards

Chris

--- In Astro_IIDC@yahoogroups.com, "milton_aupperle" <milton@...> wrote:

Hi Folks;

I have been working on a minor update to Astro IIDC for people who have  PGR Cameras with the 4 GPIO pins (that's pretty much all of them - but I have to check my notes on older models). This won't work with TIS cameras.

Basically this would replace the need for having to use a GPUSB to control the mount via the ST-4 auto guider port. That would reduce the need to have another cable running from the Mac to the mount. In my case, that would mean one FireWire 800 cable to control the imaging camera, guide camera and then control the ST4 port.

I've got the code written and verified that it works as expected. Basically it just shows up as another guider interface like the GPUSB or Serial devices do currently.

The downside is that you would not be able to use extended exposure option when this is being used. But since most cameras can do at least 30 second exposures, this won't be an issue when using it as a guider.

The only complication is that each GPIO pins have almost no (<1 milli amp) drive and have to be amplified with a transistor (NPN 3904 type) to cause the ST4 motors to run. I'm working on the hardware end of it later this week.

I can provide information on how to wire it up and part list, but might consider selling a prebuilt set up for people not comfortable with doing it themselves.

I'll keep you posted on my progress.

PS: You could also wire up two of the GPIO pins to behave as a Serial Port - but the coding and wiring for that is a lot more involved.

TTYL..

Milton Aupperle