MKS Monster8 v2 + EBB36 CAN Bus Setup Guide

i

Overview

This guide covers setting up the MKS Monster8 v2 as a USB-CAN bridge — it connects to the host computer via USB and acts as the CAN interface for toolhead boards like the EBB36. No separate USB-CAN adapter is required.

MKS Monster8 v2

MCU: STM32F407VET6
CAN pins: PB8 (RX) / PB9 (TX)
Bootloader: 32KiB offset
Clock: 8 MHz crystal
Role: USB-CAN bridge + printer MCU

BTT EBB36 v1.1 / v1.2

MCU: STM32G0B1
CAN pins: PB0 (RX) / PB1 (TX)
Bootloader: 8KiB offset
Clock: 8 MHz crystal
Role: Toolhead board via CAN
⚠️ v1.1: Remove 24V before DFU mode

ℹ️

Naming noteThe tool was renamed from CanBoot to Katapult. Use ~/katapult/ wherever a guide says ~/CanBoot/. The output file is still named canboot.bin for legacy compatibility.

⚡

BitrateThis guide uses 1000000 (1Mbit) throughout. All devices on the CAN bus must use the same bitrate.

1

Flash Katapult — Monster8 v2

Prerequisites

sudo apt install git dfu-util
cd ~
git clone https://github.com/Arksine/katapult ~/katapult
pip3 install pyserial --break-system-packages

Jumper Setup — Before Connecting USB

Jumper	Action	Reason
USB Power (VUSB)	INSTALL	Powers the board from USB 5V for initial flashing — no main power needed
CAN SELECT (×2)	INSTALL in CAN position	Routes PB8/PB9 to the RJ12 CAN port. Must be in CAN position, not I2C position

📷 View Monster8 jumper diagram (maz0r guide)

Red box = USB power jumper (install) · Green box = CAN select jumpers (install in CAN position) · Blue box = RESET button

Put the Board in DFU Mode

Connect via USB-C. Then: hold BOOT0, tap RESET, release BOOT0.

lsusb | grep "0483:df11"
# Expected: STMicroelectronics STM Device in DFU Mode

📷 View expected DFU mode lsusb output (maz0r guide)

Configure and Build Katapult

cd ~/katapult
make menuconfig

📷 View Katapult menuconfig for Monster8 (maz0r guide)

Use these settings but change CAN bus speed to 1000000

Setting	Value
Micro-controller Architecture	STMicroelectronics STM32
Processor model	STM32F407
Bootloader offset	32KiB bootloader
Clock Reference	8 MHz crystal
Communication interface	CAN bus (on PB8/PB9)
CAN bus speed	1000000

make clean && make

Flash Katapult

sudo dfu-util -a 0 -D ~/katapult/out/canboot.bin \
  --dfuse-address 0x08000000:force:mass-erase:leave -d 0483:df11

ℹ️

Expected errordfu-util: Error during download get_status after "File Downloaded Successfully" is normal. The firmware flashed successfully.

Verify Katapult is Running

Double-tap the RESET button, then check:

lsusb
# Expected: ID 1d50:6177 OpenMoko, Inc. stm32f407xx

ls /dev/serial/by-id/
# Expected: usb-katapult_stm32f407xx_XXXX-if00

📷 View expected Katapult USB output (maz0r guide)

Note the serial device path — needed for the next step

2

Flash Klipper — Monster8 v2 (USB-CAN Bridge)

Configure Klipper

cd ~/klipper
make menuconfig

Klipper menuconfig for Monster8 v2 — USB-CAN bridge on PB8/PB9 at 1000000 baud

Setting	Value
Enable extra low-level configuration options	Yes [*]
Micro-controller Architecture	STMicroelectronics STM32
Processor model	STM32F407
Bootloader offset	32KiB bootloader
Clock Reference	8 MHz crystal
Communication interface	USB to CAN bus bridge (USB on PA11/PA12)
CAN bus interface	CAN bus (on PB8/PB9)
CAN bus speed	1000000

⚠️

Communication interface must be USB-CAN bridgeSetting this to plain "USB" will NOT create a can0 interface on the host. It must be "USB to CAN bus bridge (USB on PA11/PA12)".

🚫

Do not use alternate CAN pinsPA8/PA9 (EXT_1 header) and the dedicated CAN header TX/RX pins will not work — they are not connected to the STM32 hardware CAN peripheral. Only PB8/PB9 (RJ12 port) works reliably.

make clean && make

Flash via Katapult

Double-tap RESET to enter Katapult mode, then flash:

python3 ~/katapult/scripts/flash_can.py -d \
  /dev/serial/by-id/usb-katapult_stm32f407xx_<YOURID>-if00

📷 View successful Klipper flash output (maz0r guide)

3

Set Up CAN Interface on Host

Kernel Requirement

The host kernel must have gs_usb support. Verify:

sudo modprobe gs_usb && echo "gs_usb available"
# If this fails, enable CONFIG_CAN_GS_USB=y and rebuild kernel

Configure can0

sudo nano /etc/network/interfaces.d/can0

allow-hotplug can0
iface can0 can static
 bitrate 1000000
 up ifconfig $IFACE txqueuelen 256
 pre-up ip link set can0 type can bitrate 1000000
 pre-up ip link set can0 txqueuelen 256

Jumper Change — Before Connecting 24V

Jumper	Action	Reason
USB Power (VUSB)	REMOVE	Prevents back-feeding 5V through USB when 24V main power is connected. Failure to remove can damage the board.
120R termination	INSTALL	Terminates the Monster8 end of the CAN bus. Required when the Monster8 is at one physical end of the bus.

Reboot, then connect the Monster8 via USB and apply 24V power.

lsusb | grep "1d50:606f"
# Expected: OpenMoko, Inc. Geschwister Schneider CAN adapter

ip link show can0
# Expected: can0: <NOARP,UP,LOWER_UP,ECHO> ... state UP

📷 View expected lsusb output with CAN adapter (maz0r guide)

Verify Monster8 on CAN Bus

~/katapult/scripts/flash_can.py -i can0 -q
# Expected:
# Detected UUID: XXXXXXXXXXXX, Application: Klipper

✅

Note the Monster8 UUID — you will need it for printer.cfg.

📷 View expected CAN query output (maz0r guide)

4

Flash Katapult — EBB36 v1.1 / v1.2

🔥

v1.1 ONLY Heater warning — remove 24V before DFU mode The BOOT pin is shared with the heater output on the EBB36 v1.1. Entering DFU mode while 24V is connected will activate the heater. Remove 24V power before proceeding. The v1.2 board does not have this issue.

Jumper Setup — Before Connecting USB

Jumper	Action	Applies To	Reason
USB Power	INSTALL	v1.1 + v1.2	Powers the EBB36 from USB for DFU flashing

Put the EBB36 in DFU Mode

v1.1 Disconnect 24V power first. Then connect via USB.

v1.2 Connect via USB. 24V power state does not matter.

Hold BOOT, tap RESET, release BOOT.

lsusb | grep "0483:df11"
# Expected: STMicroelectronics STM Device in DFU Mode

Configure and Build Katapult

cd ~/katapult
make menuconfig

Katapult menuconfig for EBB36 v1.1 / v1.2 — STM32G0B1, CAN on PB0/PB1, 1000000 baud

Setting	Value
Micro-controller Architecture	STMicroelectronics STM32
Processor model	STM32G0B1
Bootloader offset	8KiB offset
Clock Reference	8 MHz crystal
Communication interface	CAN bus (on PB0/PB1)
CAN bus speed	1000000
Support bootloader entry on rapid double click	Yes [*]

ℹ️

Small binary size is expectedThe canboot.bin for STM32G0B1 is approximately 4304 bytes. This is correct — the bootloader is genuinely that small for this MCU.

make clean && make

Flash Katapult

sudo dfu-util -a 0 -D ~/katapult/out/canboot.bin \
  --dfuse-address 0x08000000:force:mass-erase:leave -d 0483:df11

The EBB36 will disappear from USB after flashing — this is expected. Katapult runs in CAN-only mode with no USB presence.

Jumper Change — Before Connecting to CAN Bus

Jumper	Action	Applies To	Reason
USB Power	REMOVE	v1.1 + v1.2	Board will now be powered by 24V via the CAN cable
120R termination	INSTALL	v1.1 + v1.2	Critical. The EBB36 is at the end of the CAN bus. Without this jumper the EBB36 will not communicate on the CAN bus at all. Jumper is near the CAN connector, labeled 120R.

🚫

Missing 120R jumper is the most common mistakeIf the EBB36 does not appear in the CAN query, check the 120R termination jumper first.

Verify Katapult on CAN Bus

Connect the EBB36 to the CAN bus. Apply 24V power via the CAN cable.

~/katapult/scripts/flash_can.py -i can0 -q
# Expected:
# Detected UUID: XXXXXXXXXXXX, Application: Klipper    ← Monster8
# Detected UUID: YYYYYYYYYYYY, Application: Katapult   ← EBB36

⚠️

EBB36 not appearing?Double-tap the RESET button. The bootloader has a brief window before jumping to the application. Try several times — the timing is finicky.

✅

Note the EBB36 UUID — you will need it for printer.cfg.

5

Flash Klipper — EBB36 v1.1 / v1.2

Configure Klipper

cd ~/klipper
make menuconfig

Klipper menuconfig for EBB36 v1.1 / v1.2 — STM32G0B1, CAN on PB0/PB1, 1000000 baud

Setting	Value
Enable extra low-level configuration options	Yes [*]
Micro-controller Architecture	STMicroelectronics STM32
Processor model	STM32G0B1
Bootloader offset	8KiB bootloader
Clock Reference	8 MHz crystal
Communication interface	CAN bus (on PB0/PB1)
CAN bus speed	1000000
Optimize stepper code for step on both edges	Yes [*] (recommended)

make clean && make

Flash via CAN

Ensure the EBB36 shows Application: Katapult in the CAN query, then:

python3 ~/katapult/scripts/flash_can.py -i can0 \
  -f ~/klipper/out/klipper.bin -u <EBB36_UUID>

Verify Both Boards Running Klipper

~/katapult/scripts/flash_can.py -i can0 -q
# Expected:
# Detected UUID: XXXXXXXXXXXX, Application: Klipper   ← Monster8
# Detected UUID: YYYYYYYYYYYY, Application: Klipper   ← EBB36

📷 View expected final CAN query output (maz0r guide)

6

printer.cfg

[mcu]
canbus_uuid: XXXXXXXXXXXX  # Monster8 UUID

[mcu EBB36]
canbus_uuid: YYYYYYYYYYYY  # EBB36 UUID

Future Firmware Updates (OTA via CAN)

Once Klipper is running, future updates require no USB connection:

# Put EBB36 into Katapult mode
python3 ~/katapult/scripts/flash_can.py -i can0 -u <EBB36_UUID> -r

# Rebuild and flash
cd ~/klipper && make
python3 ~/katapult/scripts/flash_can.py -i can0 \
  -f ~/klipper/out/klipper.bin -u <EBB36_UUID>

!

Troubleshooting

Symptom	Likely Cause	Fix
`can0: No such device`	`gs_usb` not loaded	`sudo modprobe gs_usb` — if fails, rebuild kernel with `CONFIG_CAN_GS_USB=y`
`Unable to bind socket to can0`	Interface not up	`sudo ifup can0`
Monster8 shows as `0483:df11` after flash	Katapult not running	Double-tap RESET button
EBB36 not in CAN query	Missing 120R termination jumper	Install 120R jumper on EBB36 near CAN connector
EBB36 not in CAN query	No 24V power	Verify 24V wiring to EBB36 power input
EBB36 not in CAN query	Katapult jumped to app	Double-tap RESET — timing is finicky, try several times
Heater activating during DFU v1.1	BOOT pin shared with heater	Remove 24V power before entering DFU mode
No CAN traffic (`candump can0` empty)	CANH/CANL swapped	Swap the two CAN signal wires
No CAN traffic	Wrong CAN pins in firmware	Rebuild Monster8 with PB8/PB9, not PA8/PA9
WiFi lost after kernel rebuild (Surface RT)	mwifiex was a kernel module	Rebuild with `CONFIG_MWIFIEX=y` and `CONFIG_MWIFIEX_SDIO=y`

MKS Monster8 v2 + BTT EBB36 v1.1 / v1.2

Overview

MKS Monster8 v2

BTT EBB36 v1.1 / v1.2

Flash Katapult — Monster8 v2

Prerequisites

Jumper Setup — Before Connecting USB

Put the Board in DFU Mode

Configure and Build Katapult

Flash Katapult

Verify Katapult is Running

Flash Klipper — Monster8 v2 (USB-CAN Bridge)

Configure Klipper

Flash via Katapult

Set Up CAN Interface on Host

Kernel Requirement

Configure can0

Jumper Change — Before Connecting 24V

Verify Monster8 on CAN Bus

Flash Katapult — EBB36 v1.1 / v1.2

Jumper Setup — Before Connecting USB

Put the EBB36 in DFU Mode

Configure and Build Katapult

Flash Katapult

Jumper Change — Before Connecting to CAN Bus

Verify Katapult on CAN Bus

Flash Klipper — EBB36 v1.1 / v1.2

Configure Klipper

Flash via CAN

Verify Both Boards Running Klipper

printer.cfg

Future Firmware Updates (OTA via CAN)

Troubleshooting