PID control goes crazy when enabling steppers

Basic Information:

Printer Model: Anycubic Kobra 2 neo
MCU / Printerboard: Trigorilla Gen v4.0.1
Host / SBC: old i386 intel atom vipnet terminal (2 cores 1024 ram)
klippy.log klippy (1).log (267.4 KB)

Describe your issue:

PID control goes crazy when enabling steppers
But when steppers are disabled all is normal
Tried calibrating it many times but still not working

video youtube . com / watch?v=8EUBGwCe_3Y
type manually because it says new users can only put 2 links in a post (but it is currently 2 links lol)

Holy hell that is old.

Also, Run PID Calibration for your extruder, your derivative value is way too high and it causes it to bounce around like that.

https://www.klipper3d.org/G-Codes.html#pid_calibrate_1

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not working, i wrote that i calibrated it many times
i enabling steppers and it starts bouncing
BUT when i disable steppers it stabilizes
klippy (2).log (1.2 MB)
(i calibrated it now with steppers enabled)

when steppers are disabled it is keeping at 10-20% stable
but when steppers are enabled it is bouncing around 0%-50% quickly

Why do i have a feeling something in your wiring is causing interference

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maybe
but the stock firmware somehow keeps the temperature stable
and i did not disassemble or modify the printer

not working, i wrote that i calibrated it many times

You have no SAVE_CONFIG area in your klippy_log, you might have ran autotune but you didn’t run “SAVE_CONFIG” once it ran or it would have updated your printer.cfg.

PID control is just a software layer which is analyzing input behavior and driving output.

So explanation for crazy behavior is crazy behavior of your thermistor data - input.

You can try to query analog values which klipper is getting from your board and converting it to temperature by executing command

QUERY_ADC NAME=extruder

most probably you will see same crazy behavior of analog values.
You can check if it’s real hardware behavior by connecting voltmeter to your thermistor and monitor voltage behavior.

If you will confirm that it’s hardware behavior - then you need to troubleshoot hardware issues.

Possible hardware issues:
Wiring issues, unstable ADC reference voltage, unstable power supply, faulty thermistor, EMP interference.

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You either have a wiring or even power issue or when it runs fine with Marlin (I guess) your Atom Terminal might not be the fastest causing erratic behavior.

What are the MCU loads during such operations?

3-10% of cpu load

yes i think there is some interference in wiring or somewhere else, is there a way to apply filter to pid control?
(also, although it bouncing a lot, it keeps the temperature pretty stable within 204-206 at 205 target )

Ok, so you understand that you have hardware issue - good.
You want to ignore it - bad.

To summarize your request: “I’m very bothered with jumping temperature graph in UI which is caused by malfunctioning hardware, can I do something so I would not see it ?”

Short answer: Yes, remove checkbox “Show chart” in fluid UI settings. - this will hide the temperature graph.

:slight_smile:

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