Driver overheat message but sensor 0C

jphilly

I'm using a Maestro with the 2 driver expansion module. One of the drivers on the module reports overheating to the console but the drivers sensor doesn't show it, it just stays at 0C. Are the drivers on the module not measured by the sensor or is something gone wrong?

Phaedrux

The drivers don't report a temperature, just a flag saying normal, warning, and overtemp. So 0c would mean it's back to normal I believe.

Are the drivers themselves actually getting hot?
What current are you running them at?
Are they actively cooled?

jphilly

Last time this happened I touched the pcb and it was warm, so the overheat message isn't erroneous.
The driver should be running at 900mA which is below their max.
They are thermostatically cooled: the fan starts at 40 and will be at 100% at 65. The fan monitors the driver overtemp flag and the mcu temp. Problem is, despite the warnings on the console, the flag didn't raise and turn on the fan as it should have. Even when the driver was overheating the graph and reading didn't change as it should have.

Argo

@jphilly

You could add small heatsinks to the TMC chips.
That helps enormous.

jphilly

@Phaedrux This is what I get, note the graph and driver sensor.

jphilly

@Argo Doesn't seem like there's room on the bottom of the expansion for a heatsink

Phaedrux

@jphilly said in Driver overheat message but sensor 0C:

They are thermostatically cooled: the fan starts at 40 and will be at 100% at 65. The fan monitors the driver overtemp flag and the mcu temp.

It might be more effective to monitor bed and hotend temps so that whenever a print is happening and a temp is above 45c the fan will turn on.

dc42

@jphilly said in Driver overheat message but sensor 0C:

I'm using a Maestro with the 2 driver expansion module. One of the drivers on the module reports overheating to the console but the drivers sensor doesn't show it, it just stays at 0C. Are the drivers on the module not measured by the sensor or is something gone wrong?

Thanks for reporting this. This is a bug, which I've fixed in time for the 3.3beta3 release. The drivers on the 2-driver board were assigned to a different temperature reading channel, but there was no way to access that channel. I've changed it to put all 7 drivers on the same channel. I think this makes most sense, because a single fan will normally be used to cool both the Duet and the daughter board.

To cool the Duet Maestro or Duet 3 Mini, we recommend a small fan at the edge of the board that blows air along the line of driver chips on both side of the board. When using the 2-drive daughter board, it should also blow air along both sides of that board too.

jphilly

@dc42 Thanks for the fix, I'll try the beta when it releases