Servo for Pebble Wiper
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Re: Servo on a Duet 2 Wifi + Duex5
Re: Getting Servo WorkingI am in the process of setting up a [KST DS215MG](file:///tmp/mozilla_arden0/DS215MG%20V3.0%20Datenblatt%20.pdf) server for the Pebble Wiper on my E3D Toolchanger with Duet 2 Wifi and Duex 5 (RRF 3.3) and am encountering similar issues to the forum posts linked above (the forum warned me they were old topics and suggested I create a new one). My pin configuration is as suggested by @dc42 just with PWM_5 instead.
M950 S0 C"duex.pwm5"If I use M42 as suggested I can the signal output change from around 0.16V at S0 to around 0.59V at S255 and it does not increase beyond that. I assume these measured voltages with a DMM are due to the PWM duty cycle, unfortunately I don't have a scope with which I can check the frequency and peak voltages, however I assume if I do the math on the frequency/duty cycle it's where it should be.
When I enable the pin the LED for the heater associated with the PWN pin turns on and 24V is present on those pins (obviously with no load since there is nothing connected). I don't think this question was ever answered, is it expected that the heater pin LED lights up? I've noticed the brightness of that LED varies with the PWM strength as well.
So I'm seeing some variation on the signal pin of the PWM output and I can see a steady 5V the voltage pin, however no amount of commanding the stepper with M280 will get it to move. The stepper I have specifies it's working frequency as 1520us/333Hz, 800us-2200us. It looks like the default PWM frequency is 50Hz, I've tried changing this with the Q parameter of M950, however at 333Hz this doesn't seem to help.
In the Pebble Wiper configuration they seem to use a PWM fan output instead of a real PWM header and then control the server with fan commands instead of the M280. Not sure if this is because they couldn't get it working over PWM but I think they are using Duet 3 as well. The frequency used there is 600Hz for some reason.
I haven't been able to find any specifications for the stall current of this particular servo, however I assume I'll want to add the capacitor and diode per the guide on the Wiki just in case.
If anyone has any bright ideas on what I could try next it would be appreciated.
