(Note that I have posted an almost identical message on Discord, but I think this is probably a much better place for it. I don’t think that Discord is the best place for non-real-time messaging.)
There has recently been a bit of activity on Discord, GitHub and seemingly here relating to some reported TMC UART anomalies. I have been using the Duet3D Mini with TMC2209 for a while now and I have initially experienced a number of unrelated issues, all related to significant modifications I installed on my printer at the same time as the Duet Mini installation, the learning curve, etc. All these issues have now been resolved except for two randomly occurring “glitches”.
One of the glitches that I have seen a few times now is related to TMC UART. The difference is that in my case it generally happens extremely infrequently (once every few weeks), it always happens on the same TMC driver (z1 in my config), and it has now happened with two different Duet Mini boards. Another common theme is that it appears to happen when homing after the printer has been powered up and not printing for extended periods of time. I have never seen any errors during printing.
It is also worth noting that in the first attached case there has been a brief power outage overnight that I believe restarted the printer. Unfortunately I am not able to determine the duration of the power outage, but I do know that the Raspberry Pi power supply in my printer has a much shorter hold-up time than the main 24V power supply.
The attached logs show the above referenced event as well as another event that just occurred this morning. Both happened when I tried homing the printer after it has been powered up and idle for some time. I would appreciate if anyone could shed some light on what might be going on…
I have been chasing some EMI issues on the printer, but in this case I don’t believe that EMI is the issue. It always happens on Z1 stepper and thus far always after homing following prolonged idle time.
klippy - Unable to read tmc uart ‘stepper_z1’ register IFCNT - 2021-06-27.zip (173.0 KB)