Hi all, Modifying Marlin to work with my CNC setup running on RAMPS1.4, namely configuring the spindle speed control to D6 PWM. I have a chinese speed controller that accepts a PWM input via optocoupler. However it looks like it uses Mach 3 (~12V VPP 1,000-10,000 Hz as shown by the documentation I was able to hunt down. Scaled up the voltage from PWM via P55NF06L with 10k pull-up, voltmeter says the 0-12V PWM works nicely (yay). Problem is frequency is way too slow by the look of things. When PWM is off, Spindle reads ~0V. But then no matter how I scale it, it's always stuck at 52V. I read that PWM on all pins is 490/980Hz by default, but can be adjusted up to 8MHz by adjusting the timers. Then reading into some Marlin documentation I discover that D6 uses TIMER4A. This looks like a custom timer breakout that doesn't quite fit the naming convention I've seen elsewhere on guidance for changing frequency.
Essentially I'm a little bit in over my head, looking to get pin D6 running at say, 5kHz, smack-bang in the middle of the accepted Mach3 range, and I would love any guidance on how!
Thank you very much for your time :D
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