Variable Frequency Pulse Needed

[Greg_R]

PIC18F65J15
50Hz to 1kHz with at least 7 bits

My circuit has a stepper motor controller/driver that requires a pulse for each step. The speed has to be ramped but is otherwise constant for long periods of time. I want to avoid using an interrupt as it will fire every 1 to 20 ms. I'm shooting for a nice deterministic main loop...

The PWM frequency options look to be too coarse and too fast.

I didn't see a way to set the Compare function so that it would both reset the timer and toggle the CCP pin.

Any ideas?

Greg

[Greg_R]

10Mhz Crystal with 4xPLL
Design is not in layout yet so any pin can be made available.

Greg

[SherpaDoug]

Try googling "numerically controlled oscillator". I did one on a 20MHz 16C58 PIC that went up to 35kHz.
_________________
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[Greg_R]

SherpaDoug,

Thanks for the suggestion but unless I missed something it doesn't answer the question. I'm simply looking for ways to avoid using an interrupt. Everything else the circuit needs to do will fit into a simple task schedule.

Greg

[Greg_R]

Turns out the compare modules on the dsPIC33s will do exactly what I need. Good thing the system also has one of them...

Greg