Andrew,

If you're looking for recommendations, I'd pick #3. It keeps the control of the motors in the same place that does the measurement of where the antennas currently are. The tighter that loop is the more accurate will be your positioning, and the more tolerant it will be of interface glitches. Alternative #1, as you say, is too hard (unless you're really into that sort of thing), and #2 and #4 could send the rotor into the end stops (risking fatal damage) if the Linux box were to get confused or out of sync with the PIC.

Finally, with #3 you can make a stand-alone manual controller, to do custom things like parking the antennas if the weather turns bad, or creating a bunch of pre-set buttons for favorite positions, all without needing to fire up the PC.

Good luck,

Greg KO6TH

From: vk4tec@tech-software.net To: amsat-bb@amsat.org Date: Wed, 21 Oct 2009 20:24:07 +1000 Subject: [amsat-bb] PIC sat tracker

Putting together a USB 16F877 rotator control A/D serial and LOGIC

Got a few options

Predict as the AZ/EL engine and perl scripts.

1. Completely autonomous - quite hard to do in a PIC
2. Use the A/D and just send data back to LINUX and get LINUX to turn relays on / off via parra port
3. Send AZ and EL to the PIC, do a ASCII to BIN and then get the PIC to drive the rotators.
4. Use the A/D and send data to LINUX and then send back a serial command on what to do.

Cheers

Andrew VK4TEC

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