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FLY-SB2040 V3 Bootloader (Katapult) Recovery

For unbricking recovery only

The FLY-SB2040 V3 comes pre-flashed with Katapult from the factory. When using normally and updating Klipper firmware, do not re-flash the firmware on this page; this page is only for unbricking recovery after the Bootloader is damaged.

Firmware Description​

Name Description

Katapult was formerly named CanBoot; both may appear simultaneously in old tutorials or old firmware names.

Katapult is the bootloader used to boot and update Klipper:

  • Katapult itself cannot be used as a Klipper MCU; after flashing, the Klipper firmware matching the hardware and communication method still needs to be written.
  • The method for entering Katapult is subject to the current product page: boards with a RESET button can enter by quickly double-pressing RESET; boards with only a BOOT button require fully powering off first, then holding BOOT while connecting USB, and releasing it once the device is recognized. After entering, there is usually a status LED blinking.
  • CAN, RS232, and USB use mutually independent Katapult firmware and cannot be mixed by simply changing the file name or using them directly.
  • CAN firmware must also select the correct bus rate; common rates are 500K and 1M.
  • The FLY-SB2040 V3 supports CAN and RS232 communication.
  • This page provides Katapult firmware for two CAN speeds: 500K and 1M.
CAN Speed Must Match

Select only one firmware that matches your actual CAN network speed. The host, motherboard, and all CAN devices on the same bus must use the same speed.

Entering Flash Mode​

Power Off

Before starting, completely turn off the printer and disconnect the power supply. Do not plug/unplug cables, arrange wiring, or touch terminals while the system is powered on.

In the diagram, the left button is RESET, and the right button is BOOT:

  1. Keep the tool board completely powered off.
  2. Press and hold the BOOT button.
  3. Connect the tool board to your computer or host using a Type-C cable that supports data transfer.
  4. Release the BOOT button once the device is recognized.
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Flashing Firmware​

  1. Confirm that the device has entered UF2 flashing mode, and a removable disk named RPI-RP2 appears on the computer.
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  1. Release the BOOT button or remove the BOOT jumper.
Windows file extension display

Windows may hide file extensions. Please check "File name extensions" in File Explorer, and confirm that you are using .uf2 firmware; do not modify the firmware extension.

  1. Download the Flash erase firmware:

The directory of the erase firmware in the repository is:

FLY-Firmware/RP2040

  1. Copy nuke_universal.uf2 to the RPI-RP2 disk to erase the old firmware already present on the device.

  2. After the copy is complete, the RPI-RP2 disk will automatically disappear; after the device erases the Flash, it will appear again as an RPI-RP2 USB drive, and at this point the Flash is already empty.

  1. Download the FLY-SB2040 V3 Katapult firmware:

The firmware directory in the repository is:

FLY-Firmware/ToolBoard/SB2040
  1. Copy the Katapult .uf2 firmware to the newly appeared RPI-RP2 disk.
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  1. After the firmware is written, the RPI-RP2 disk will automatically disappear, indicating that Katapult has been flashed successfully.

After Flashing​

Power Off

After flashing is complete, disconnect the tool board's USB and external power supply before restoring normal wiring. Do not connect or disconnect tool board cables while powered on.

After powering on again, the status LED will blink when Katapult starts normally:

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