[amsat-bb] Re: PIC rotator control

Marc Vermeersch amvm at skynet.be
Tue Oct 13 04:44:36 PDT 2009

Hi Andrew,

I have a PIC based solution currently in the prototype stage. It uses a
PIC18F4455 and drives a Yeasu AZ/EL rotor without the Yeasy control box. 

The PC sends information to the PIC (RequestedAZ,RequestedEL) and the PIC
sends back status information to the PC

Everything is done by the PIC:
- Control of the rotor motors based on either move-every-n-seconds or
- Measurement of the actual AZ/EL with 10-bit resolution
- Parking when no signal has been coming from the PC in x seconds -or- an
explicit park command is received
- Stall protection
- Some horizon protection: EL cannot go below x when AZ is y to avoid
pointing into my neighbors' bedroom.
- Over the top rotor control (under development)
- ...

I'm using a PIC18F4455 and it is very well capable of doing all that and
more. I have chosen this path for several reasons:
- Eventually I want to run a tracking algorithm in the PIC too
- To make the control loop shorter
- To avoid dependence on the PC part specifically on safety related aspects
like stall control and horizon protection. 
- To explore the capabilities of the PIC18
- (Because it's my job to do embedded HW/SW)


> -----Original Message-----
> From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
> Behalf Of Andrew Rich
> Sent: dinsdag 13 oktober 2009 12:22
> To: amsat-bb at amsat.org
> Subject: [amsat-bb] PIC rotator control
> Hello
> I am re-visting a rotator controller.
> I am curious, should I push the processing of the "compare and make a
> decision" onto the PIC, or pull that function back into the PC ?
> I/O is serial
> PIC is 16F877
> Andrew VK4TEC
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the
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