Ender 3 Pro v4.2.7 stock firmware build - thermistor calibration bug

Marlin Firmware Service Firmware Builder
1

Hardware setup under test:

  • Ender 3 Pro, 4.2.7 32-bit board, stock screen, filament runout sensor v2

Firmware under test:

Issue:

  • Bed thermistor is not calibrated correctly, even though the bed heats up correctly and the thermistor was verified separately and working. This firmware build either:
  1. alerts with “bed failure to heat” or
  2. thermal runaway bed heating error and issues a loud beep.
  • possibly an eeprom config issue in the ender 3 pro 4.2.7 build? (see attempt to resolve)
  • hot end heat and temperature measurement work fine.

Resolution attempts:

  • when I reinstall the barely functioning Creality firmware for the v4.2.7 board, the eeprom is reset and the bed heater + temp measurement of the bed work fine.
  • Next I will try to build Marlin myself for the hardware config above and see how far I get.

Am I the only one seeing this issue?
Is there a calibration step required for the bed heat thermistor?
Is there another build that has been verified to work properly with stock bed and heat measurement?

2

Likely the PID parameters have changed - so its a good idea to retune the bed heater calibration for the PID algorithm.

A quick search shows me this link as a guide:

You should also be able to trigger this from the screen if you don’t have a way to connect a PC to the printer.

EDIT: This has steps on how to do it from the screen only:

3

Cool, thanks for the rapid response and lesson about PID (proportional integration derivative) tuning. I learned something new today, :sunglasses:

But I think there may be something pretty basic that is wrong with the eeprom resulting from your build config for the Ender-3 Pro v4.2.7 stock.

I just pulled the latest code from this Marlin branch on github:

  • Marlin bugfix-2.1.x tonight my time, your morning (link stripped)
    • I would have provided a github link but since I am new to your community I am limited to 2 links per post, maybe this post will score me some credits with ya… :upside_down_face:
    • I reserved my two allowed links for you to consider the more useful bits below.

I started with the basic Marlin config for an Ender 3 Pro v4.2.7 board from the config repo:

  • Marlin Config bugfix-2.1.x (link stripped)

I followed this pretty decent YouTube tutorial to learn how to customize a Marlin config and build the firmware from raw source:

  • Compiling Marlin 2.1.x for Ender Series 3D Printers! | The Complete How-To Guide | Updated 2023 (link stripped)

I tweaked a few things to add filament runout detection support (which requires ADVANCED_PAUSE_FEATURE and NOZZLE_PARK_FEATURE be activated as well). Here is my Marlin config, if you are curious to test it out and see what’s wrong with your build system:

The resulting firmware build:

Results from installing the custom firmware build:

  • Installed but with an error up front:
    • indicating the eeprom was corrupt and needed to be updated
    • This is the eeprom that was installed after loading a build from this site.
  • I tested 2 builds from your automated build system:
    • 27 Dec 2024
    • 9 Jan 2025
    • …same heatbed temp issue with both.
  • I overwrote the eeprom with the one from the custom build
  • I did not do any PID reconfiguration and things worked fine:
    • no heatbed temp failures
    • no false thermal runaway failures

I am 3 hours into a long test print, :crossed_fingers: :crossed_fingers: the print would have failed by now.

Thanks for all you do to support Marlin builds for other printers. I hope my Ender 3 Pro notes, Marlin config and test firmware build help your community. Have a good one, sir!

4

Any time the featureset changes in a firmware, the eeprom data should be invalidated.

My firmware should auto-reset the values if they don’t seem sane - ie why you don’t get prompted - it just performs an auto-reset.

It’s recommended that PID tuning be done any time you do a major firmware change - even if its just features included.

The failures you mentioned can all be caused by incorrect PID settings.

5

:+1:

Ultimately my firmware build failed after 4 hours. It just locked up with now warning or errors posted, stopped printing and turned off the hotbed and extruder nozzle :no_mouth:

I will follow you counsel, try the PID tuning and let ya know, thanks mate for the 1-on-1 troubleshooting advice!

6

CRCinAU you were totally correct, mate. PID calibration was the key and quite simple to figure out. All good now! No issues with current Marlin builds. Thank you for piecing together this great build service! And the 1-on-1 trouble shooting!

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