Have a bit of a mystery on my hands. At MD States one our team members took the 12V power into to a motor controller and plugged it into one of the motor outputs and turned the robot on. Resulting symptoms:
- Three of the four MR motor controllers on the bot showed “yellow” on the Core Device Discovery. They also would not report their Firmware version number. Firmware version number should have been 2.0. We had all modules upgraded this past summer.
- PDM was blown. Single LED showing. I’ve seen this in the past as a result of reversing the polarity of the input power. Though it is difficult say with certainty, don’t really see how the team could have done this.
I hooked each motor controller up to Core Device (V2.1.1) and “upgraded” them. They now show green and the proper firmware version. PDM is toast.
I am in an email discussion w/ MR and they are stating that the 12V supplies are isolated from the USB signal and USB 5V supply. This makes sense as it is normal engineering practice. They are also stating that the only way to get a single LED is to reverse the polarity on the output. I’ve asked for specifics about what causes the single LED condition. But it seems like there could be a ton of things to cause this.
So my questions:
- Anyone experience this sort of cascading failure? My expectation would be that the single motor controller would have been fried vs. having three motor controllers need re-programming. I would have thought that the PDM would be unaffected as well.
- It appears that somehow the flash on the motor controller got corrupted. Has anyone seen this?
- Has anyone experienced a “single LED” condition on the PDM that was not caused by reversing polarity?
I am asking so the team can use this as a learning condition. We are also progressing to Regionals and don’t know if I trust these re-flashed motor controllers. Any other thoughts are welcome as well. In advance, thanks!!