This page still in progress because I don't have all the information for BMCU on P series.
Update 5th May
In firmware versions :
01.08.00.00 for the P series
01.09.00.00 (20250429) for the X seriesBambulab has added support for the updated AMS model like AMS 2, which involved changes to the communication protocol between the AMS system and the printer.
As a result, BMCU currently does not function properly (e.g., unable to modify filament settings). It is unclear how soon BMCU's author will respond to these changes. If you intend to keep your P/X printer updated with the latest firmware, we recommend not relying on BMCU at this time.
The A-series is not affected at the moment, according to Bambulab the adaptation programme for the newer AMS for the A-series is still a few months away.
¶ BMCU Version Adaptation Status
- BMCU-A: Not supported; no plans for future adaptation.
- BMCU-B: Fully supported and running well on the P-Series.
- BMCU-C: Testing.
¶ Original BMCU firmware with P/X printer
Starting from firmware version 2-6, the BMCU firmware is capable of identifying whether your printer belongs to the P/X series or A series. In the original firmware developed by @4061N, the logic for P/X series printers is as follows:
-
Feeding: Identical to the A series, no special handling.
-
Unloading: When unloading is triggered, the filament is retracted until the BMCU's filament detection mechanism (optical sensor or steel ball-based) no longer detects the filament. At that point, the unloading stops, the motor briefly reverses direction and feeds forward for 100ms to reinsert the filament slightly into the BMCU.
Under this default behavior, a rewinder is required to take up the slack, as the filament will be pulled out by a significant length.
This also means that, provided you have a compatible rewinder setup, you are free to upgrade your BMCU to any firmware version.
¶ Without rewinder system
For setups without a rewinder, there are some special firmwares modified by @XC. Unlike the original firmware which relies on filament detection (e.g., optical or steel ball sensors), this version uses a time-based retraction mechanism to define the unloading distance.
This approach results in a shorter retraction distance.
Note: Previous documentation have inaccurately stated otherwise. In reality, the default behavior causes the filament to retract all the way until it exits the BMCU, whereas this modified firmware only retracts until it reaches the internal or external five-way connector.
¶ Using externe 5 way
You will need a bambu 4-in-1 ptfe adapter or anything similar.
¶ Using internal 5 way
¶ Firmwares
These firmwares are modified by XC @星尘
¶ BMCU-B
¶ 3.14
Externe 5 way:
Internal 5 way:
¶ BMCU-C
¶ 4.24
Using internal 5 way:
- P_Hall_4_24_Int5Way.bin.zip - Different springs required:
WD0.6 OD12 L30 mmfor buffer andWD0.6 OD4 L15for lever
¶ Using AMS + BMCU or more than one BMCU
This is a theoretical assumption made by the developer and a few others. In reality, due to the less number of P-series users and even fewer who are interested in using AMS with BMCU—I have never received any feedback on this topic, especially regarding the connection of the BMCU to the AMS Hub and the conversion from a 4-pin to a 6-pin cable.
I must warn you that attempting this is 100% at your own risk. I strongly advise against trying it without prior experience in electronics or circuit design.
(Of course, if you do succeed, you're more than welcome to share your results with the community—it would help many others who are interested!)
¶ AMS + BMCU
The principle of the BMCU is to directly simulate the AMS device to communicate with the printer, it is possible to use AMS + BMCU on the P-Series, (I can't say for sure for newer devices like AMS 2)
See the official Bambulab tutorial for using two AMS https://wiki.bambulab.com/en/x1/manual/Connect-AMS-Hub-and-multi-AMS
Since the BMCU only has one 4pin connector, you need to connect the AMS directly to the AMS Hub, and then connect the BMCU to the AMS.
Please refer this interface diagrame:
¶ 2*BMCU
Please note that it is not possible to use two BMCUs directly on the P-Series.
Altertive : BMCU-Hub to connect 4 BMCUs-> to update