Dead PWM Channels
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Would like to get some ideas on what could lead to 2 PWM channels dying on what was a working quad when it landed. When arming for a second flight I noticed two motors weren't turning. After troubleshooting up the signal chain, I could confirm the output of PWM2 and PWM3 had no output no matter what setting/command was attempted. I flashed to PX4 in case it was an Ardupilot issue, but still have no output on PX4.
I can move to channels 5/6 with no issue, but I'm a little concerned that without identifying root cause I may be placing other channels at risk. Any ideas on troubleshooting steps, or things that could have caused it? There were no shorts that I could measure and the PWM and ESC are on the same ground reference.
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Hi @tangotoo ,
If you have a DMM handy, can you confirm you get a high resistance reading between the PWM output pins and DGND on J7 with the PCB powered OFF and disconnected from the ESCs?
Pin 10 is DGND.
For example, if you measure DCR on Pin-2 to GND (pin-10), you should get ~200-300KOhm. And for Pins 3-9 as well.
If any of those are much lower, then that implies an ESD or overvoltage event might have damaged the pins from the STM MCU or the ESD protection devices we have creating an internal short in the MCU or on the ESD diodes on those specific bad channels.If all the readings are in that high value range for all 8 PWMS, then our SW team will have to jump in to help.
Thanks!
