DMC 60c glitching PWM

[Cameron Tacklind]

I have a DCM 60 C motor controller in my project. It is being driven by the PWM output channel of a raspberry pi at 3.3 V. Normally this works fine.

Every once in a while, particularly under high for the system’s load (under 5A), The light pattern will start flashing alternating red from top to bottom. This, as I understand it, indicates that the motor controller is not receiving a PWM signal. Using an oscilloscope, I can confirm the PWM signal is getting to the motor controller because I am injecting it on one pair of pins and sensing it on another pair.

I am having a very difficult time figuring out why it believes it does not think it is receiving a PWM signal. If I remove the PWM signal and reapply, the controller does not recover. I have to power cycle the whole controller for it to recover.

I am wondering if maybe some glitching data on the data wires makes the controller think it is receiving a CAN signal, switching to CAN control mode, and refusing to switch back until a power cycle.

Can someone confirm that this is what’s happening? Or maybe something else is happening?

[JColvin]

Hi @Cameron Tacklind,

What range of pulse width are you using for the DMC60C? I believe the CAN mode has it's own command that it needs to start, but I have reached out to another engineer to get their thoughts on this.

Thanks,
JColvin

[Cameron Tacklind]

My apologies for the slow reply. I didn't see the response.

1500us +/- 900us. at 1000us it would sometimes not register the pulses.

Now the motor controller is stuck in a perpetual flashing state.

What does the circuit at the input look like? Is it isolated? I'm wondering if I could possibly have burned out my processor's GPIO.

Could I use 12V "logic levels" in a pinch for the input? Are there any pull ups/downs internally?