Monday, August 28, 2006
I grafted the second CPU on the XY controller board to handle 1 KHz PWM signals to run one of the plastic gearmotors. If I don't get some answers back from Microchip that give me some more elegant options the board will get another 16F628A CPU to run the other plastic gearmotor and we will have Cerberus. :-o
UPDATE: The bad news is that Microchip didn't have any good news for me.
The good news is that I've discovered that I have some three-post resonators rated at 4 and 10 MHz. I'm going to pull that 20 MHz crystal and try out the three-poster resonators and see if I can find a usuable PWM frequency. If I do I'm going to see if I can get the board running properly at the lower frequencies.
I hate losing the performance, but hey? What's the choice?
If you're going to divy up the work among separate PIC16F628A chips anyway, seems like they'd have plenty of CPU, RAM, and Instruction ROM to handle your needs?
This seems it was the original idea with RepRap, anyway, for synchronising the various motors. I'm not sure where the clock was generated there, though (perhaps at the comms controller?)
What I'm doing is exploring another part of the space of potential solutions to controlling a cartesian reprap. If my way doesn't work and the mainline method does, I can always go back and use the mainline method.
OTOH, if the mainline approach fails for some reason or another we have the possibility of another way of doing the job that will already have been designed and tested that the mainline people can turn, too.
What this does is improve the overall potential for success of the RepRap project.
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