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Tip
  • MMU provides Katapult firmware for both USB and CAN connections; you can flash it yourself if needed
  • MMU comes pre-flashed with Katapult firmware for CAN connection at a rate of 1M
  • Flash Katapult Firmware

Firmware Flashing Instructions

  • MMU can connect to the host computer via RS232, CAN, or USB
  • RS232 and CAN require an XT30(2+2)-F connector, while USB requires a TYPE-C data cable with data transfer capability
  • Below is the XT30(2+2)-F data cable style
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Important Note
  • Flashing firmware to the mainboard requires using Katapult to flash Klipper
  • If you are certain that Katapult has already been flashed to the mainboard, you do not need to flash the Katapult firmware at the end
  • You can quickly press the reset button twice and check if an LED on the mainboard blinks; if so, it indicates the mainboard has entered Katapult firmware

How to Determine Which Firmware You Need​

  • MMU can connect to the host computer using the following methods
  • Flash CAN Firmware
    • Advantage: If Katapult firmware is flashed, firmware updates can be done without touching the mainboard, and bus connection is supported
    • Disadvantage: May cause errors like homing timeout when used together with KlipperScreen
    • Tip: To use CAN, ensure the host computer supports CAN and is paired with a UTOC or a mainboard with bridged firmware
  • Flash RS232 Firmware
    • Advantage: No special software is needed; communication is reliable and stable
    • Disadvantage: To reflash the firmware, you need to enter manual DFU or double-press RST to enter Katapult for firmware updates
    • Tip: Requires pairing with a G2T or UTOR for use
  • Flash USB Firmware
    • Advantage: If Katapult firmware is flashed, firmware updates can be done without touching the mainboard. If using a memory card or DFU flashing, the original method is still needed. Communication is reliable and stable
    • Disadvantage: Multiple USB devices may affect data transmission

Katapult Firmware Explanation​

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.
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