Any thoughts on what might have caused this 6HC to go sideways?

oozeBot

My personal dev system (photo below) has been sitting on my desk running happily for well over a year now completely sealed as shown. It has never had any motors connected to it (or anything else) nor had any known events that might have caused power spikes, etc. Last week, I found it doing this: Recording 2025-04-15 114733.mp4

I guess I can't embed a video, so if you don't want to click the link, all six drivers are erroring with "over temperature shutdown, phase A short to ground, phase B short to ground." over and over..

edit to answer the obvious - the board is cool to the touch. There is no signs of anything being "over temperature" and there is a cooling fan built in blowing directly on the board from behind.

Perhaps something @dc42 can weigh in on? FYI - replacing the board immediately resolved the issue, so it's definitely the board.. Thanks

elmoret

That sounds like SPI failure, the microcontroller can't talk to the stepper drivers.

dc42

@oozeBot it's either an SPI failure or a failure of power to the drivers. The SPI data signal goes from pin 105 of the MCU to pin 15 of driver 0. Then from pin 16 of driver 0 to pin 15 of driver 1, then from pin 16 of driver 1 to pin 15 of driver 2 and so on until pin 16 of driver 5 is connected to the MCU pin 32.

The SCLK signal goes from pin 46 of the MCU to pin 14 of every driver. The CS signal goes from pin 74 of the MCU to pin 13 of every driver.

The drivers take 3.3V power on pin 20 and 12V power on pin 4. Caution: if you try to measure 12V power on pin 4 and in the process you short it to pin 5, you will destroy the driver. A safer way to check for 12V power to driver 5 is to measure it on capacitor C110. There should also be 5V on capacitor C116.

I suggest you start by checking that driver 5 is receiving power, and that all three of its connections to the MCU are intact.

oozeBot

Thank you both! I'll have an engineer do some testing on it. We've never seen one have this kind of issue before and would like to understand if we (really, myself since it's been on my desk) caused it damage or if it was just a faulty board. I'll go ahead and remove the "Unsolved" tag.