Skip to main content

FLY-SHT36 V3 Bootloader (Katapult) Recovery

For unbricking recovery only

The FLY-SHT36 V3 comes with Katapult pre-flashed from the factory. Do not re-flash the firmware on this page during normal use or Klipper firmware updates; this page is only for unbricking recovery after the Bootloader is corrupted.

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-SHT36 V3 supports CAN and RS232 communication.
  • This page provides Katapult firmware for two CAN rates: 500K and 1M.
CAN Rate Must Match

Select only the firmware that matches the actual CAN network rate. The host, mainboard, and all CAN devices on the same bus must use the same rate.

Entering Bootloader Mode​

Power Off Required

Before starting, completely turn off the printer and disconnect the power supply. Do not plug or unplug wiring harnesses, rearrange connector wire order, or touch terminals while powered on.

The FLY-SHT36 V3 board only has a BOOT button and no RESET button. Do not press or double-press RESET; to enter bootloader mode, only follow the BOOT procedure below. The arrow in the image points to the BOOT button:

  1. Keep the tool board completely powered off.
  2. Press and hold the BOOT button.
  3. Use a Type-C cable with data transfer capability to connect the tool board to a computer or host.
  4. Once the device is recognized, release the BOOT button. A RPI-RP2 disk will appear on the computer (under Linux / FLYOS, it is a mount point with the same name).
Loading...

Flashing Firmware​

  1. Confirm that the device has entered UF2 flashing mode, and a removable disk named RPI-RP2 appears on the computer.
Loading...
  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-SHT36 V3 Katapult firmware:

The firmware directory in the repository is:

FLY-Firmware/ToolBoard/SHT36
  1. Copy the Katapult .uf2 firmware to the newly appeared RPI-RP2 disk.
Loading...
  1. After the firmware is written, the RPI-RP2 disk will automatically disappear, indicating that Katapult has been flashed successfully.

Complete Flashing​

Power-off Operation

After flashing is complete, disconnect the tool board USB and external power supply first, then restore normal wiring. Do not plug or unplug the tool board wiring harness while powered on.

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

Loading...
Klipper Firmware Still Needs to Be Flashed

The status LED blinking only indicates that Katapult is running normally; at this point there is no Klipper firmware on the board yet. Please return to the Firmware Compilation and Flashing page and flash the corresponding firmware according to the actual connection method (CAN or RS232).

Loading...