Tip

The MMU provides Katapult firmware with USB and CAN connections, which can be flashed as needed.
The MMU is pre-flashed with Katapult firmware for CAN connection at a rate of 1M.
Katapult firmware flashing

Firmware Flashing Instructions

The MMU can be connected to the host computer using three connection methods: RS232, CAN, and USB.
RS232 and CAN require a XT30(2+2)-F for connection, while USB requires a TYPE-C data cable with data transfer capability.
Below is the style of the XT30(2+2)-F data cable.

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Important Notes

Klipper must be flashed via Katapult when writing the motherboard firmware.
If you confirm that Katapult is already flashed on the motherboard, there is no need to flash the Katapult firmware in the final step.
You can quickly press the reset button twice and check if an LED on the motherboard starts blinking. If it does, the motherboard has entered the Katapult firmware.

Selecting the Firmware Type

Please confirm the connection method first.

If a CAN toolboard is needed: select CAN firmware.
If an RS232 connection is needed: select RS232 Firmware.
If a CAN toolboard is not used and a direct USB connection is needed: select USB firmware.
Only one of the three firmware types can be selected; do not flash multiple types simultaneously.

Firmware Type	Applicable Scenario	Advantage	Confirm Before Selecting	Operation
CAN Firmware	When a CAN toolboard is needed	Supports multiple devices on the CAN bus	Confirm the host supports CAN and prepare a UTOC or USB-CAN bridge board	Compile CAN Firmware
RS232 Firmware	When an RS232 connection is needed	Stable communication, simple configuration	Requires an RS232 connection device such as G2T or UTOR	Compile RS232 Firmware
USB Firmware	When a direct USB connection is needed	Stable communication, simple configuration	Confirm that the host's USB port and data cable communicate properly	Compile USB Firmware

Name Explanation

Katapult was formerly known as CanBoot, and both names may appear simultaneously in older tutorials or firmware names.

Katapult is a bootloader used to boot and update Klipper:

Katapult itself cannot be used as a Klipper MCU; after flashing, you still need to write Klipper firmware that matches the hardware and communication method.
Supported tool boards can enter Katapult by quickly double-pressing the RESET button; after entering, there is usually a status light blinking.
CAN, RS232, and USB use independent Katapult firmware; you cannot simply modify file names or mix them directly.
For CAN firmware, you must also select the correct bus speed, with common speeds being 500K and 1M.