Report 40°C on virtual TMC heater channel for any driver being active

[wilriker]

This one closes https://forum.duet3d.com/topic/5536/status-based-fan-mode - if I did not miss anything where else it would be required to check for an non-disabled driver. ;-)

[wilriker]

I have amended this commit as I forgot to add the const modifier to the new method that checks if any driver is currently active/idle.

[dc42]

I cannot accept this PR as it stands because it doesn't distinguish between drivers that are on the Duet, drivers that are on a DueX2 or DueX5, and external drivers. Each virtual heater channel should show 50C only when relevant drivers are active.

[wilriker]

I will fix that on Thursday. Thanks for spotting.

[wilriker]

While adjusting this I found something strange. There are up to 10 drivers when using Duet+DueX5. But there is constexpr size_t DRIVES = 9; in Pins_Duet.h and this limits it to only 9 drivers max. Why is that? How is the last driver on DueX5 used at all?

Everything I found related to drivers has only a length of 9 including the enable step and direction pins.

What am I missing? I was missing that there are several definitions of this constant. 🤦‍♂️ Out of some reason they are hidden in Project Explorer view of eclipse.

[wilriker]

Fixed. This will now check a maximum of 5 drivers per board. This means it will never check drivers 10 and 11 unless there will be a third board requested.

[wilriker]

Any update on accepting this one?

[dc42]

Thanks for the reminder. Why did you choose 50C? The complication I can see is that if you have a fan set to run thermostatically on both CPU temperature and driver temperature, you can only choose one temperature for both. So the value we choose to report for drivers that are active matters.

[wilriker]

50C was just the logical gap between the existing

• 0C: everything OK
• 100C: warning
• 150C: critical

Do you have any recommendation for a better value? My only idea right now is to set it at the value when it would be recommended for the CPU to be cooled. So e.g. if it is recommended to cool the CPU once it reaches 42C then set this value also to 42C. This way if the drivers are off but the CPU reaches this temperature out of whatever reason (extensive simulations, pointing a heat-gun at it?! ;-) ) cooling would still start as necessary.

[wilriker]

I thought about the temperature a little and I think 35C or 40C would probably be a better temperature in regards to thermostatically controlled fans that also monitors CPU. 35C might be a bit over-cautious but I think 40C would be good.

What do you think?

[wilriker]

I have updated this PR to the latest commit on dev branch since there were some incompatible changes sometime in between. I also hid the method checking for active drivers behind

#if HAS_SMART_DRIVERS
...
#endif

and let it only check up until MaxSmartDrivers instead of MaxTotalDrivers. This can be easily changed back in case this method needs to be used somehow on Duet 0.6/0.85.

Also I lowered the returned temperature to 40°C.