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SKR Pro 1.2, powering stepper drives introduce temperature reading fluctuations


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Good evening,

I own BTT SKR Pro 1.2 board wired to the Xinkebot Orca 3 IDEX 3D printer. As the machine had a ton of flaws, I heavily modded it, and one of upgrades were replacing stock crap extruders with BIQU H20 extruder, along with switching stepper drivers from 2209 to BTT TMC 5160 Pro.

Machine is working fine, beside one annoying detail. When the steppers are disabled, termistor readings for extruder 1 and 2 are rock solid, no matter hotends are cool or heated to set temperatures. They naturally, slowly oscillate +-1 degree.

But its enough to enable the steppes, no matter X, Y, Z or Extruders, and temperatures start to wander up and down +-10 degrees. From 210 suddenly dropping to 197, just to read in next second 205, and so on and so on. Randomly swaying up and down and showing random values around set temperature. It is not related to the heating and PID tuning, its impossible for the hotend block to suddenly cool 15 degrees in a second, just to jump back to 205 in another one and then dwell down to 192 again. Especially that as soon as I hit "Disable Steppers" button, all fluctuations are gone and temperatures become stable again. Same happens when hotends are not heated at all and rest in room temperature. Enabling steppers cause the nominal 19 degree to oscillate as well.

My guess is, that stepper drivers introduce some kind of electric noise to the board, which disrupts termistors readings. Not need to mention that it cause a chaos for the board to keep set temperature when in every second there is different reading, above or below set temperature, resulting in chaotic heating and cooling of the hotend and then reflecting it on quality of the prints.

Is there any solution for it?

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