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M105 Temperature Report Format  

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ScottW
(@scottw)
Reputable Member
M105 Temperature Report Format

The M105 temperature report from the MK4 looks like this:

    Recv: T:26.50/0.00 B:23.93/0.00 X:25.11/36.00 A:38.55/0.00 @:0 B@:0 HBR@:0

T and B are standard, Toolhead and Bed respectively.  And X appears to be the heatbreak.   What is A?

Posted : 11/07/2023 12:32 am
jkavalik
(@jkavalik)
Member
RE: M105 Temperature Report Format

According to the source, A is the board temperature (from "ambient" probably).

https://github.com/prusa3d/Prusa-Firmware-Buddy/blob/master/lib/Marlin/Marlin/src/module/temperature.cpp#L3670

Posted : 11/07/2023 9:29 am
ScottW liked
ScottW
(@scottw)
Reputable Member
Topic starter answered:
RE: M105 Temperature Report Format

Thank you for finding that. I had guessed it might be the board or cpu, but did not find the code -- and also didn't see much change when giving the board some load (like uploading a large print and rendering it for the display).  Appreciate the help!

Posted : 11/07/2023 4:06 pm
jkavalik
(@jkavalik)
Member
RE: M105 Temperature Report Format

No problem. I suppose simple upload is handled fine, I would probably try rendering multiple previews (opening the web-ui and loading all files thumbnails, but they may be cached, and the network is slow enough that it might be idling anyway).

Posted : 11/07/2023 5:00 pm
ScottW
(@scottw)
Reputable Member
Topic starter answered:
RE: M105 Temperature Report Format

I couldn't get the "A:" temp to move much with any kind of processing loads. 

I could not find a schematic for the MK4 buddy board but did find one for the mini.  It has a board-mounted thermistor (TH1, NTCG104LH104JTDS) located adjacent to the heatbed connector.  I'm guessing they put it there to monitor the heat produced by the high-current load connection going to the heatbed.

And sure enough, when I powered up the bed heater, the "A:" temp begins rising (slowly but steadily).  After disabling the bed heater, the "A:" temp stabilized and then began falling.

So at this point (or until I get a mk4 board schematic) I am going to guess the "A:" is reporting board temperature near the heated bed connector. 

Posted : 11/07/2023 5:56 pm
jkavalik
(@jkavalik)
Member
RE: M105 Temperature Report Format

Makes sense. It is definitely not "cpu" temperature, so even if it reacts to load, it only averages over longer times anyway.

Posted : 11/07/2023 6:07 pm
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