Bambu-Bus

Tools & Documentation relating to the Bambu Bus

Introduction

The bambu-bus is a proprietary protocol, based on UART through a RS485 bus
The UART is clocked at 1228800bps with 1 even parity bit and 1 stop bit

Headers and Devices Adressing

The bambu bus is using 2 packet formats,
The long header packet, which has data indication the master and slave between multiple avaible devices
And The short header packet, which communicate between 1 preset master and slave

these packets are usually comprised of a start byte 3D, a packet lenght indicator, and an 8 bit CRC for verifying the header integrity.

Long form header

Byte number	Content	Bytes occupied
0	0x3D	1
1	Flag(less than 0x80)	1
2~3	Packet sequence	2
4~5	Total packet length L	2
6	CRC8 for all previous bytes [1]	1
7~8	Target address	2
9~10	Source address	2
11~(L-3)	Packet content	L-13
(L-2)~(L-1)	CRC16 for all previous bytes [2]	2

[1] CRC8 generation polynomial: 0x39, initial value 0x66, no XOR and reverse.
[2] CRC16 generation polynomial:0x1021, initial value 0x913D, no XOR and reverse, but low byte first in the array.

adressing relations

Address Number	Meaning
Address Number	Meaning
0x03	MC (motion controller)
0x06	AP (The first type of upper computer, in the X series)
0x07	AMS
0x08	TH
0x09	AP2(The second type of upper computer, in the P and A series)
0x0E	AHB
0x0F	EXT (May be external control board)
0x12	AMS lite
0x13	CTC

short form header

Byte number	Content	Bytes occupied
0	0x3D	1
1	Flag and sequence (bigger than 0x80)	1
2	Total packet length L	1
3	CRC8 for all previous bytes [1]	1
4	Packet type	1
5~(L-3)	Packet content	L-7
(L-2)~(L-1)	CRC16 for all previous bytes [2]	2

[1] CRC8 generation polynomial: 0x39, initial value 0x66, no XOR and reverse.
[2] CRC16 generation polynomial: 0x1021, initial value 0x913D, no XOR and reverse, but low byte first in the array.

The data type of the short frame header (collected in AMS lite, so the content listed is intended for AMS lite):

Value	The (possible) meaning
0x03	Read the movement information of the filament
0x04	Read and change the AMS lite motion status
0x05	Verify that the device is online
0x06	Unknown
0x07	Read the NFC information
0x20	Printer heartbeat packet

Tooling

Parsers

• Protoparser.py -> packet parser, works best for the X1 serie packets

Simulators

• AMCU -> AMS emulator written by researcher 4061N

Research team:

• 4061N
• leonllrmc