[amsat-bb] Re: PIC rotator control

John Mock KD6PAG kd6pag at amsat.org
Thu Oct 15 20:47:28 PDT 2009

> 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 ?
> PC is LINUX 
> I/O is serial 

I built a homebrew rotator controller, inspired by WB4APR 'Radio Shack' rotor
controller.  But given that both convention serial and parallel ports are no
longer available on most laptops, and alot less common elsewhere, i decided to
use a USB PIC.  Initially, that was a EPROM-based PIC16C475 but later migrated 
to the flash-programmable PIC18F2550.  It also includes a serial port, so that
a laptop could talk to a TTL-level serial port radio.  

My intent was to put the pointing smarts into the PIC, but i never got that
far.  Currently, it reads the rotor position inside the PIC, but moving the
rotor in software (for both LINUX and Windows). That much works, but i bogged
on the PIC side trying to adapt Microchip's composite USB driver code to work
properly with multiple devices.  There were reliability issues, whose details
i have forgotten, that put the whole project, which included a distributable
version, onto the back burner.

I'm sorry i can't be more helpful than that.  Eventually, i'll get back to
this project, and amateur satellites in general.

			  -- KD6PAG  (Networking Old-Timer, Satellite QRPer)

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