FLY-SHT36 V2 Bootloader (Katapult) Recovery

For Brick Recovery Only

The FLY-SHT36 V2 is pre-flashed with Katapult from the factory. Do not re-flash the firmware on this page during normal use or Klipper firmware updates; this page is only for brick recovery after a corrupted bootloader or for explicitly needing to update Katapult.

Firmware Description

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.

• FLY-SHT36 V2 uses only CAN communication.
• This page provides Katapult firmware for both 500K and 1M CAN bus speeds.
• FLY-SHT36 V2 comes in STM32F072, APM32F072, and STM32F103 MCU versions. Flashing methods cannot be mixed.

Confirm the MCU model first

• STM32F072: Can be flashed via DFU on Windows, Linux, or FLYOS.
• APM32F072: Can only be flashed using DFUProgrammer on Windows.
• STM32F103: This page only supports online updates if the original Katapult can still communicate via CAN.

Both the firmware model and CAN bus speed must match the actual hardware, the host, and other CAN devices on the same bus.

Entering Bootloader Mode

This step applies only to the STM32F072 and APM32F072. STM32F103 online updates do not require entering USB DFU mode.

Power Off Operation

Before starting, completely shut down the printer and disconnect the power supply. Do not plug/unplug wiring, rearrange connector pinouts, or touch terminals while powered on.

The BOOT pad is indicated in the figure:

1. Keep the toolboard completely powered off.
2. Short the BOOT pad with a jumper cap.
3. Connect the toolboard to a computer or host using a Type-C cable that supports data transfer.
4. Remove the BOOT jumper cap once the device is recognized.

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Flashing the Firmware

• Windows
• Linux / FLYOS

• STM32F072
• APM32F072

Download the STM32F072 Katapult firmware:

• FLY_SHT36V2_072_CANBOOT_500K.bin
• FLY_SHT36V2_072_CANBOOT_1M.bin

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。

• STM32CubeProgrammer
• DFU-AUTO

Power-off operation

Before connecting or reconnecting the USB cable, completely turn off the printer and disconnect all other power supplies. Do not let the tool board be powered simultaneously through the printer power supply and the USB interface.

USB connection compatibility

The USB interfaces on some computers may cause unstable flashing due to driver or signal compatibility issues. If the connection fails, try using a different USB interface on the computer or use a reliable-quality USB dock; when the error shown below appears, also check the USB connection and driver first.

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1. Download and install SetupSTM32CubeProgrammer and the STM32 DFU driver from the auxiliary software download page.
2. Save the firmware downloaded on this page to a location on your computer that is easy to find.

Windows file extension display

Windows may hide file extensions. In File Explorer, check "File name extensions" to confirm that the firmware is still .bin or .hex, and do not change the file extension.

3. Confirm that the device has entered DFU flashing mode according to the product tutorial, then connect it to the computer using a USB cable that supports data transfer.
4. Open STM32CubeProgrammer, select USB mode, refresh the device list, and connect.

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5. If no error pop-up appears, the connection is successful.

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6. Click the download icon on the left, and check the flashing options as shown in the figure below.

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7. Click Browse and select the firmware to be flashed.

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8. When flashing .bin firmware, set Start address to 0x08000000; when using .hex firmware, keep the address included in the file.

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9. Click Start automatic mode to begin flashing.

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10. When the success prompt appears, the firmware flashing is complete.

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Power Off Before Operation

Before connecting or reconnecting the USB cable, completely power off the printer and disconnect other power sources. Do not let the toolboard be powered simultaneously by both the printer power supply and the USB interface.

1. Download and run FLY DFU-AUTO.
2. If the "Driver Status" shows unavailable, click "Install Driver" to complete the WinUSB driver installation.
3. Click "Browse" to select the .bin firmware file to be flashed.

Windows File Extension Display

Windows may hide file extensions. In File Explorer, check "File name extensions" to confirm the firmware remains as .bin. Do not modify the file extension.

4. Click "Start Flashing", monitor progress through the run log, and wait for the flashing process to complete.

Detailed Tutorial: FLY DFU-AUTO Download and Usage

Download the Katapult firmware for APM32F072:

• FLY_SHT36V2_072_CANBOOT_500K.bin
• FLY_SHT36V2_072_CANBOOT_1M.bin

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。

Power-off operation

Before connecting or reinserting the USB cable, please completely turn off the printer and disconnect other power supplies. Do not let the tool board be powered simultaneously through the printer power supply and the USB interface.

1. Download and extract DFUProgrammer from the Auxiliary Software Download Page.
2. Manually install the APM32 DFU driver included in the toolkit.
3. Save the firmware downloaded on this page to a location on your computer that is easy to find.

Windows file extension display

Windows may hide file extensions. Please check "File name extensions" in File Explorer, confirm that the firmware is still .bin, and do not modify the file extension.

4. Confirm that the device has entered DFU flashing mode according to the product tutorial, then connect it to the computer using a USB cable with data transfer capability.
5. Open DFUProgrammer and select the device and firmware as shown in the figures below.

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6. Click "Start updating firmware" and wait for the progress to complete. After the success prompt appears, power off and restore the wiring according to the "Complete flashing" requirements on this page.

• STM32F072 (DFU)
• STM32F103 (CAN update)

• Linux
• FLYOS

1. Install flashing tool.

   sudo apt update
   sudo apt install dfu-util -y

2. Confirm the device has entered DFU flashing mode.

   lsusb

   If you can see 0483:df11, it means DFU flashing mode has been entered successfully.

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3. Pull/update firmware repository.

   git clone https://cnb.cool/3dmellow/FLY-Firmware ~/FLY-Firmware
   cd ~/FLY-Firmware && git pull --ff-only

4. Flash firmware.

   FLY_SHT36V2_072_CANBOOT_500K.bin

   sudo dfu-util -a 0 -d 0483:df11 --dfuse-address 0x08000000 -D ~/FLY-Firmware/ToolBoard/SHT36/FLY_SHT36V2_072_CANBOOT_500K.bin

   FLY_SHT36V2_072_CANBOOT_1M.bin

   sudo dfu-util -a 0 -d 0483:df11 --dfuse-address 0x08000000 -D ~/FLY-Firmware/ToolBoard/SHT36/FLY_SHT36V2_072_CANBOOT_1M.bin

5. If File downloaded successfully appears, flashing is successful.
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1. FLY host computer usually has dfu-util built-in, no need to install flashing tool again.
2. Confirm the device has entered DFU flashing mode.

   lsusb

   If you can see 0483:df11, it means DFU flashing mode has been entered successfully.

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3. Pull/update firmware repository.

   git clone https://cnb.cool/3dmellow/FLY-Firmware /data/FLY-Firmware
   ln -s /data/FLY-Firmware /root/FLY-Firmware
   cd /data/FLY-Firmware && git pull --ff-only

4. Flash firmware.

   FLY_SHT36V2_072_CANBOOT_500K.bin

   sudo dfu-util -a 0 -d 0483:df11 --dfuse-address 0x08000000 -D /data/FLY-Firmware/ToolBoard/SHT36/FLY_SHT36V2_072_CANBOOT_500K.bin

   FLY_SHT36V2_072_CANBOOT_1M.bin

   sudo dfu-util -a 0 -d 0483:df11 --dfuse-address 0x08000000 -D /data/FLY-Firmware/ToolBoard/SHT36/FLY_SHT36V2_072_CANBOOT_1M.bin

5. If File downloaded successfully appears, flashing is successful.
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Must retain a communicable Katapult

This method updates the existing Katapult via CAN. Use it only if the toolboard can still enter Katapult and its CAN UUID can be queried; do not proceed if the bootloader is corrupted or CAN communication is unavailable.

1. Pull or update the firmware repository.

• Linux
• FLYOS

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

If already downloaded, run:

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

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

If already downloaded, run:

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

2. Query the CAN UUID of the toolboard in Katapult mode:

~/klippy-env/bin/python ~/klipper/lib/katapult/flashtool.py -q

3. Replace <CAN_UUID> in the commands with your actual query result, then execute only ONE command based on your CAN bus speed:

CAN 500K:

~/klippy-env/bin/python ~/klipper/lib/katapult/flashtool.py -f ~/FLY-Firmware/ToolBoard/SHT36/FLY_SHT36V2_103_CANBOOT_500K.BIN -u <CAN_UUID>

CAN 1M:

~/klippy-env/bin/python ~/klipper/lib/katapult/flashtool.py -f ~/FLY-Firmware/ToolBoard/SHT36/FLY_SHT36V2_103_CANBOOT_1M.BIN -u <CAN_UUID>

If lib/katapult/flashtool.py is not available on older systems, use these compatible commands:

CAN 500K:

~/klippy-env/bin/python ~/klipper/lib/canboot/flash_can.py -f ~/FLY-Firmware/ToolBoard/SHT36/FLY_SHT36V2_103_CANBOOT_500K.BIN -u <CAN_UUID>

CAN 1M:

~/klippy-env/bin/python ~/klipper/lib/canboot/flash_can.py -f ~/FLY-Firmware/ToolBoard/SHT36/FLY_SHT36V2_103_CANBOOT_1M.BIN -u <CAN_UUID>

Finishing the Flash

Power Off Operation

After flashing is complete, disconnect the toolboard's USB and external power before removing the BOOT jumper cap and restoring normal wiring. Do not plug or unplug the toolboard wiring while powered on.

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

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