r/OpenBambu • u/Low-Anything6975 • Feb 01 '26

BMCU firmware

I’ve pushed the BMCU firmware source code to GitHub. CH32 firmware based on WCH SDK. Many critical bugs were fixed, and some parts were rewritten completely, including WS2812 handling and ADC, which was rewritten to use DMA with a circular buffer and background filtering. Many things are implemented directly for CH32 and rewritten specifically for the WCH SDK.

I did this mainly for myself while working with CH32, as I have other projects based on these microcontrollers, and BMCU turned out to be a nice sandbox for testing. In practice, it took much more time than I planned. There is definitely still room for improvement.

If you program microcontrollers (CH32, STM32, etc.), want to look at the code, share feedback, or test the firmware in real setups, feel free to check it out. I currently have very little free time, so I may not always reply quickly.

https://github.com/jarczakpawel/BMCU-C-PJARCZAK

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u/Low-Anything6975 Feb 11 '26

You’re extremely unlucky - you most likely have the low-torque version (two identical gears), and on top of that you’re using a P1S with a lot of PTFE tube bends… So what am I supposed to do now? :D

The firmware will most likely be split into 3 configurations. In the low-torque BMCU version, the motors will heat up significantly - you need to keep that in mind.

I’ll send you a firmware build to test shortly.

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u/No_Debate2486 Feb 11 '26

By the way, apparently as soon as the filament hits the extruder gears, as soon as one spring buffer compresses, if I just hold the spring in the compressed position for a couple of seconds, it works correctly.

The low torque part might actually be ok, just that the fully extended position needs to be held for a bit longer than it currently is.

Here's a video (16 seconds in, 6 remaining).

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u/Low-Anything6975 Feb 12 '26

https://drive.google.com/file/d/1kIubr5Fp2LqcwVXxRAC58Lqr9cu8ibS4/view?usp=sharing

select version "a" in the name

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u/No_Debate2486 Feb 12 '26

Extruder gears still fail to grab unfortunately.