FLY-SHT36 LIS3DH Bootloader (Katapult) Recovery

For unbricking recovery only

The FLY-SHT36 LIS3DH comes with Katapult pre-flashed from the factory. Do not re-flash the firmware on this page during normal use or when updating Klipper firmware; 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-SHT36 LIS3DH uses CAN communication.
• This page provides Katapult firmware for two CAN rates: 500K and 1M.

CAN rate must match

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

Entering Bootloader Mode

Power Off Before Operation

Before starting, completely power off the printer and disconnect the power supply. Do not plug or unplug wiring harnesses, organize interface wiring, or touch terminals while powered on.

The BOOT pad is indicated in the figure:

1. Keep the tool board completely powered off.
2. Use a jumper cap to short the BOOT pad.
3. Connect the tool board to your computer or host using a Type-C cable that supports data transfer.
4. After the device is recognized, remove the BOOT jumper cap.

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Flashing Firmware

• Windows
• Linux / FLYOS

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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2. 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.

3. Download the Flash erase firmware:

• nuke_universal.uf2

Windows 默认可能隐藏文件扩展名。下载后请确认文件扩展名未被修改，不要保存成 .txt 或其他扩展名。

The directory of the erase firmware in the repository is:

FLY-Firmware/RP2040

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

5. 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.

6. Download the FLY-SHT36 LIS3DH Katapult firmware:

• FLY_SHT36LIS3DH_CANBOOT_CAN_500K.uf2
• FLY_SHT36LIS3DH_CANBOOT_CAN_1M.uf2

Windows 默认可能隐藏文件扩展名。下载后请确认文件扩展名未被修改，不要保存成 .txt 或其他扩展名。

The firmware directory in the repository is:

FLY-Firmware/ToolBoard/SHT36

7. Copy the Katapult .uf2 firmware to the newly appeared RPI-RP2 disk.

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8. After the firmware is written, the RPI-RP2 disk will automatically disappear, indicating that Katapult has been flashed successfully.

1. Compile the RP2040 flashing tool. Skip this step if it has already been executed.

cd ~/klipper/lib/rp2040_flash/
make

2. Confirm that the device has entered UF2 flashing mode.

lsusb

If 2e8a:0003 appears in the output, it indicates that the device has entered RP2040 flashing mode. The device name displayed may differ across systems; the USB ID should be used as the reference.

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Device not recognized

Do not continue flashing if 2e8a:0003 does not appear. Please disconnect the device power again and repeat the steps in "Entering flashing mode" on this page.

3. Pull or update the precompiled firmware repository.

• Linux
• FLYOS

First-time download:

cd ~
git clone https://cnb.cool/3dmellow/FLY-Firmware.git

Update the repository if it has already been downloaded:

git -C ~/FLY-Firmware pull --ff-only

First-time download:

git clone https://cnb.cool/3dmellow/FLY-Firmware.git /data/FLY-Firmware
ln -s /data/FLY-Firmware /root/FLY-Firmware

Update the repository if it has already been downloaded:

git -C /data/FLY-Firmware pull --ff-only

4. Flash the erase Flash firmware to clear the old firmware already present on the device:

sudo ~/klipper/lib/rp2040_flash/rp2040_flash ~/FLY-Firmware/RP2040/nuke_universal.uf2

After the command finishes, the device will automatically restart and return to BOOTSEL / UF2 mode. lsusb will show 2e8a:0003 again, and at this point the Flash is already empty.

5. Depending on the CAN rate, execute only one of the following flash commands:

CAN 500K:

sudo ~/klipper/lib/rp2040_flash/rp2040_flash ~/FLY-Firmware/ToolBoard/SHT36/FLY_SHT36LIS3DH_CANBOOT_CAN_500K.uf2

CAN 1M:

sudo ~/klipper/lib/rp2040_flash/rp2040_flash ~/FLY-Firmware/ToolBoard/SHT36/FLY_SHT36LIS3DH_CANBOOT_CAN_1M.uf2

6. After the successful flash message appears, proceed with the power-off operation.

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Completing the Flash

Power Off Before Operation

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

After re-powering, the status LED will blink when Katapult starts normally:

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