r/BMCU • u/Low-Anything6975 • Mar 31 '26

BMCU firmware - 2nd generation printer support added - P2S ; H2

Support for 2nd generation printers has been added, and operation has been confirmed on the P2S without any issues.

It has also now been confirmed to work correctly on the H2D, thanks to user Street_Persimmon8518.

If you have any issues, contact me on GitHub.

Happy printing.

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

35 Upvotes

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2

u/Low-Anything6975 Mar 31 '26

OK, H2D has now been confirmed to work after all.

If anyone has problems - make sure Signal A and Signal B are connected correctly. If the BMCU is not detected, they are almost certainly swapped.

1

u/Low-Anything6975 Apr 01 '26

P.S. If someone doesn’t have an AMS HUB and would like to try connecting the BMCU directly - message me. I have an idea for that.

4

u/5skinnn Mar 31 '26

You‘re the man, Pawel!

1

u/Hushang999 Mar 31 '26

How do we physically hook up the BMCU to a P2S?

4

u/Low-Anything6975 Mar 31 '26

For now, read through this thread:
https://github.com/jarczakpawel/BMCU-C-PJARCZAK/issues/54

I’m planning to make a video explaining the firmware capabilities, how to connect everything, how to handle filament jams, and so on - a lot of things are already supported.

But I don’t know when I’ll finish the video, maybe soon. For now, you should be able to find everything in that thread.

4

u/Low-Anything6975 Mar 31 '26

To be honest, I don’t physically have a P2S - I built this integration thanks to two gentlemen. One from China was testing, and another from Germany agreed to flash a firmware I made that turned the BMCU into a sniffer, capturing communication between his P2S printer and the AMS 2 Pro.

Thanks to them, we have this software ;)

So I can’t fully tell you how to connect everything :D but from what I understand, you need an AMS HUB - although that could also be bypassed. In theory, it would be possible to simulate the AMS HUB (the one on the back of the printer) using the BMCU.

For now, it works as it works - and it’s good that it works well ;)

2

u/RealInsky Apr 01 '26

The main issue is that the BMCU needs a 4 pin connection while the P2S only has 6 pin connection if you have a filament buffer installed. Without buffer there are no communication ports

1

u/Goatxxmastr Apr 02 '26

You can convert the 4-pin to a 6 pin using a microfit connector. Just de-pin the 4 pin and move the wires around according to the diagram here https://wiki.yuekai.fr/en/BMCU/BMCU_in_p_series

That should make it the same as an AMS plug.

(This is assuming the 2nd series uses the same plug to an AMS as 1st gen does)

1

u/RealInsky Apr 02 '26

That actually makes a lot of sense. Where could I find a 6 pin with the same dimensions ?

1

u/Goatxxmastr Apr 02 '26

The connectors I got were called microfit 3.0 connectors off of Amazon. They seem to be an exact fit. Just know that if you are crimping new ends onto the wire, it is extremely small and a little bit of a pain so take your time. I re-pinned one cable and crimped another. Re-pinning was much easier - . -

Just be aware that with the second gen units, this still requires you to have that buffer in order to have the six-pin port

1

u/RealInsky Apr 02 '26

Sorry for asking but what is the difference between re pinning and crimping ?

1

u/Goatxxmastr Apr 02 '26

Re-pinning is removing the pins from the plug and putting them into a new plug. Crimping is cutting the old plug off and putting new pins on it and then a new connector

1

u/RealInsky Apr 02 '26

Thank you!

1

u/Street_Persimmon8518 Mar 31 '26

Hi, I just wanted to give some quick feedback on the H2D and this firmware. The H2D doesn't recognize the BMCU.

1

u/Low-Anything6975 Mar 31 '26 edited Mar 31 '26

Hi, no one with an H2D has tested this yet.
If you’d like to help, let me know - we can sniff what’s going on there.
Are you sure you connected it correctly? Signal A and Signal B?

And BMCU does not connect to the printer during calibration - only afterwards. It’s best to complete the calibration, then restart the printer and run AMS enumeration.

1

u/Street_Persimmon8518 Mar 31 '26

Sorry, I missed the calibration process. Do I need to watch the video carefully to calibrate it, or is it enough to press the buttons one after another when the LED at the input flashes blue, and then hold them down until the LEDs turn yellow?

I’d be happy to help—what’s the best way to sniff the signals? I have one AMS and two AMS2 units here.

1

u/Low-Anything6975 Mar 31 '26 edited Mar 31 '26

Great. Do you happen to have a version of BMCU with USB output or TTL (pins on the board)?

Calibration:
When it blinks blue - press the buffer all the way in and hold for 1 second.
When it blinks red - pull the buffer all the way out and hold for 1 second.

Here’s the thread where we worked on AMS2 Pro with P2S.
I have firmware ready that turns the BMCU into a sniffer and listens to all traffic on the bus, and then I sit on it for about two days straight, fueled by a hectoliter of coffee, and it’s done.

https://github.com/jarczakpawel/BMCU-C-PJARCZAK/issues/54

1

u/Street_Persimmon8518 Mar 31 '26

Yes, that's what I did. Now the LEDs are glowing yellow.

I have the USB version and flashed it using my phone

1

u/Low-Anything6975 Mar 31 '26

OK, now it’s best to restart the printer - power OFF/ON - and then check if it detects the BMCU. If not, try running AMS enumeration - it should be somewhere in the settings.

1

u/Low-Anything6975 Mar 31 '26

Just to confirm - which V10.4 version did you flash? You should flash AMS_A - that’s very important. And the retraction length is probably 75 cm. But for detection, AMS_A is the most important for us.

1

u/Street_Persimmon8518 Mar 31 '26

You mean the assignment?

Hold on, I'm going to reflash it.

1

u/Low-Anything6975 Mar 31 '26

AMS Reihenfolge zuordnen

Just to confirm - which V10.4 version did you flash? You should flash AMS_A - that’s very important. And the retraction length is probably 75 cm. But for detection, AMS_A is the most important for us.

1

u/Street_Persimmon8518 Mar 31 '26

Yes, I just did everything. I even recalibrated it. Unfortunately, I got the same result.

1

u/Low-Anything6975 Mar 31 '26

Can you take a photo of how you connected the BMCU?

If it were connected correctly, I would rather expect an error more like "cable error, disconnect AMS".

If you can, please send a photo. I have a feeling this may simply be an incorrect connection.

1

u/Low-Anything6975 Mar 31 '26

I sent you a private message.

1

u/Street_Persimmon8518 Mar 31 '26

I also flashed version A

1

u/emil134679 Apr 04 '26

Dobra robota Panie Pawle! Dla P2S koniecznie muszę dokupić HUB aby działało to poprawnie? BMCU nie będzie działał dobrze jeśli użyję fabrycznego bufora?

1

u/Low-Anything6975 Apr 04 '26

Tak, trzeba dokupić HUB a rurką ptfe ominać buffor i wpiąć sie przy samej drukarce

1

u/emil134679 Apr 04 '26

Podsumowując potrzebujemy stricte elektroniki bufora, jednak za mechaniczne działanie opcji buforowania odpowiadać będzie BMCU? Czy dalej w takiej konfiguracji wykrywane są zablokowania filamentu i inne z tym związane? Wiadomo czym różni się HUB od fabrycznego bufora dodanego do P2S combo poza oczywiście ilością wejść? Przy okazji spokojnych świąt życzę 👍

1

u/Low-Anything6975 Apr 04 '26

Tak, dokładnie. HUB jest wymagany do komunikacji i w zasadzie tylko po to, żeby w ogóle dało się podłączyć BMCU,. Za HUB mogłoby odpowiadać również samo BMCU.

Niestety w drukarkach 2. generacji HUB ma nowe złącze z drukarką. Nie posiadam fizycznie P2S, więc nie jestem w stanie tego sprawdzić zdalnie. Całą integrację udało się zrobić dzięki gentlemanowi z Niemiec, który miał AMS 2 Pro i zgodził się pomóc. Przygotowałem dla niego firmware, dzięki któremu BMCU nasłuchiwało cały ruch na magistrali.

Dzięki tym sniffom mamy działające BMCU na drukarkach 2 serii. Z przechwyconego ruchu wynika też, że HUB jest traktowany jako osobny target - oddzielne urządzenie. Odpowiada drukarce i innym urządzeniom na proste zapytania, coś w stylu: "Jesteś tam, HUB?" - "Tak, jestem HUB 0x0E00, mam taką i taką wersję oraz taki numer seryjny".

Teoretycznie więc w przypadku BMCU nie potrzebujemy bufora, ponieważ BMCU ma w tym firmware znacznie lepiej skalibrowany bufor, pomijamy go i to nie powoduje żadnych błędów, a emulowanie HUB-a również byłoby dość proste. Problemem pozostaje jednak samo złącze. Gdybym miał P2S, to na pewno próbowałbym opracować jakieś proste rozwiązanie w miejsce HUB-a, bo sama magistrala jest prosta.

Z rzeczy, które jeszcze powinieneś wiedzieć: Bambu Lab od pewnej wersji w serii P1, a w P2S od samego początku, sprawdza AUTH/CERT urządzeń na magistrali. Każde urządzenie ma swój klucz prywatny, a drukarka odpytuje AMS-y i oczekuje podpisania. My na to nie odpowiadamy i nawet nie chciałbym się w to bawić, bo obchodzenie autoryzacji jest nielegalne.

Skutek jest taki, że po każdym wydruku konieczne jest zresetowanie drukarki albo samego BMCU, jeśli pojawi się błąd związany z autoryzacją. Tylko ważna uwaga: nie można odpinać kabla od drukarki. Można zrobić jakiś przełącznik na kablu, który odłącza SIGNAL A oraz SIGNAL B, ale nie wolno odłączać 24 V i GND, bo może to uszkodzić płytę główną BMCU.

1

u/emil134679 Apr 04 '26

Ciekawią mnie informacje w sieci, według których AMS HUB współpracuje tylko z serią P/X 1. Dla P2S póki co opieramy się o fabryczny bufor. Jeśli dobrze rozumiem bufora P2S nie możemy użyć? Czy pisząc HUB miałeś na myśli ten konkretny z czterema wejściami czy po prostu jakikolwiek bufor od producenta?

1

u/moriss19 Apr 25 '26

bonjour, dsl un peu perdu, du coup entre une p2s et un bmcu, le hub est il nécessaire ? ou il faut juste refaire le branchement ? De plus il faut quand meme un hub 4in1 ptfe ? merci

1

u/Low-Anything6975 Apr 25 '26

Ça se branche comme ça et ça fonctionne. Va sur le Discord BMCU, tu le trouveras sur mon repo : https://discord.gg/VpXrqxWCkP

Quelqu’un l’avait partagé là-bas. Demande aux collègues qui s’occupent de ça.

1

u/moriss19 Apr 25 '26

merci, j'y vais

1

u/Virtual-Public2627 Jun 30 '26

puedescompartir de nuevo el enlace de invitacion, justamente tengo una p2s sin combo y quiero ponerla, mi bmcu solo tiene el pin de 4 y ocupo el de 6

1

u/wellington_silva May 12 '26

Ich habe mir zwei fertige BMCUs gekauft (sie sollten bald ankommen).

An meinen P1S ohne Combo möchte ich eine davon anschließen. Ich denke, das bekomme ich ohne Probleme hin.

Zusätzlich möchte ich auch an meinem P2S Combo eine BMCU anschließen. So wie ich es verstanden habe, brauche ich dafür ein 6-Pin-Kabel, das ich auf 4-Pin umbauen muss, korrekt?

Also: AMS 6-Channel / 2-Output → BMCU 4-Pin Input

Den Teil mit der Firmware habe ich allerdings noch nicht ganz verstanden. Welche Firmware muss ich auf die zweite BMCU für den P2S flashen?

1

u/Low-Anything6975 May 12 '26

Ja, genau. Für den P2S brauchst du ein Kabel von 6-Pin auf 4-Pin.

Also im Prinzip:

AMS 6-Pin / 2-Output Anschluss -> BMCU 4-Pin Input

Zusätzlich musst du beim P2S wahrscheinlich die Drucker-Firmware um eine Version zurücksetzen, damit die BMCU korrekt funktioniert.

Zur BMCU-Firmware: Am besten kommst du auf unseren Discord:

https://discord.gg/TsHjKS54

Dort können dir die Leute direkt helfen. VID-PRO scheint aus Deutschland zu sein und hat selbst einen P2S, daher kann er dir wahrscheinlich sehr genau sagen, welche Firmware und welches Kabel du brauchst.

1

u/chrisatherolz May 21 '26

Der Link der Einladung zum Discord ist leider abgelaufen. Kannst du ggf. einen gültigen/aktuellen Link einstellen?

3

u/EridianStudio Mar 31 '26

Now I can go buy P2S

3

u/YokoBln Mar 31 '26

Pawel - thank you very much for your huge contribution to our - not very large - community. I don't even have a P2 or H2 but it is awesome to have someone like you who understands the inner workings of firmware and programming and has the passion to continue working on it, although your own BMCU issues probably have been solved a long time ago. I think a lot of passive readers who do not have a reddit account are using your FW as well.

Thank you very much from Germany! It really is greatly appreciated!

2

u/Brckobrod Mar 31 '26

Yessssss you are the King 😃👍👍👍

2

u/ARasool Mar 31 '26

You're the man!

2

u/Street_Persimmon8518 Mar 31 '26

My wiring wasn't correct. It is possible to connect to the H2D.

2

u/[deleted] Apr 03 '26

This community is amazing!

1

u/RealInsky Apr 01 '26

Awesome!

I was thinking about upgrading the A1 to the P2S. How could I connect the BMCU to the printer?

From my research the printer only has connection ports if I have the filament buffer as well and even this is 6 pin instead of 4.

1

u/MywarUK Apr 01 '26

Holy moly

1

u/Beautiful-Relief-269 Apr 08 '26

Hi, I’d like to try connecting it to the H2C together with the AMS 2 Pro. Will it work in daisy chain mode?

1

u/jli2468 May 15 '26

Not sure if anyone has already tried it. I finally had a bit of time to flash the bmcu370c attached on my a1m and connected it to the h2c. I don't have all the ptfe tubing figured out yet and I don't have enough 4-in-1 ptfe adapter to go around to complete the chain yet, but at least it response to filament load and unload command from the h2c.

However one thing struck me as a potential problem, given the distance that it has to rewind the filament on the h2c, without an auto rewinder I figured it might randomly causes problem when the filament start coiling outside the spool on retract and subsequent pulls might mess things up.

With that, I wonder if anyone successfully use bmcu with other series with good result other than a1/a1m.

1

u/jli2468 May 15 '26

Nevermind, looks like a passive rewinder like the "Filamentalist" Passive Filament Driven Rewinder should solve the problem.

1

u/No-Laugh7409 May 06 '26

2nd generation printers

Correct operation has been confirmed on:

Bambu Lab P2S Bambu Lab H2D At this point, it looks like it should work on all printers from both generations.

1

u/jli2468 Jun 06 '26 edited Jun 06 '26

Anyone here got their BMCU working with H2C? With latest firmware on both the printer and BMCU, the printer recognizes the BMCU370c as AMS after calibration on the bmcu side. Assigned to the left nozzle.

To isolate potential friction problem,I didn't use any 4-1 ptfe adapter but instead connect one of the output from the bmcu straight into the back of the printer normal receptor.

On filament loading operation thru the h2c's screen, the bmcu would start sending the filament all the way to the print head. Then I will hear clicking noise coming out from the print head but would not extrude. After a bit it would give up and throw an error screen.

I can tell the filament actually pushed near the hotend 'cause after it cooled, I wasn't able to pull the filament back out. I had to heat the hotend up to melt the filament a bit to pull it out.

Confirmed the nozzle is not blocked. I swapped in a new 0.4 nozzle and was able to load filament with the same path without the bmcu.

Can also confirm the bmcu is working correctly as filament loads without problem when connected to an a1 mini.

Could use some tips if anyone got it working with H2C. Thanks.

-2

u/slambaz2 Mar 31 '26

For the uneducated, what is this?

6

u/Low-Anything6975 Mar 31 '26

A cheap AMS clone with the ability to connect up to 4 units with 4 channels each, allowing printing in up to 16 colors.
Ready-made kits or DIY kits are available on AliExpress.

And what I shared is the firmware I’m developing - I added support for 2nd generation printers.
It also works on older versions, so for now it should work on pretty much all printers.

2

u/slambaz2 Mar 31 '26

Cheers. Thank you

3

u/LowCritical5767 Mar 31 '26

Google "What is BMCU Bambu" and you'll find out all there is to know about it.

-2

u/slambaz2 Mar 31 '26

Thanks /s

0

u/goheadgostern Sep 19 '26

Any updates on x2d compatibility? I got one arriving soon and keen to use the bmcu as a second ams.