Katapult Firmware

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.

Tip

SHT36 V2 can only be connected via CAN
CAN firmware is provided here in both 500K and 1M baud rates

Notes

APMF072 can only be flashed via computer
STM32F103 can only be updated via the host machine

Entering Flash Mode

Tip

The circled item is the BOOT

STM32F103 does not require this step!!!!
With the motherboard completely powered off, short the BOOT pin, then connect one end of a TYPE-C cable with data transfer capability to the motherboard and the other end to your device.
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Flashing Firmware

STM32F072 Windows Flashing Tutorial
STM32F072 Host Machine Flashing Tutorial
APM32F072 Windows Flashing Tutorial
STM32F103 Klipper Firmware Update Tutorial

SHT36_V2 Katapult firmware
You can obtain the firmware via the following link:

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。

Firmware location:

FLY-Firmware/ToolBoard/SHT36

Power Off Operation

Before connecting or re-plugging the USB cable, completely shut down the printer and disconnect other power sources. Do not allow the tool board to be powered simultaneously via the printer's power supply and the USB interface.

USB Connection Compatibility

Some computer USB ports may cause unstable flashing due to driver or signal compatibility issues. If connection fails, try switching to a different USB port on the computer or use a reliable USB hub. If the error shown below appears, check the USB connection and drivers first.

Download and install SetupSTM32CubeProgrammer and the STM32 DFU driver from the Auxiliary Software Download Page.
Save the firmware downloaded from 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 to confirm the firmware is still in .bin or .hex format. Do not modify the file extension.

Confirm 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.
Open STM32CubeProgrammer, select USB mode, refresh the device list, and connect.

If no error popup appears, the connection is successful.

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

Click Browse and select the firmware to be flashed.

When flashing .bin firmware, set Start address to 0x08000000. When using .hex firmware, keep the address embedded in the file.

Click Start automatic mode to begin flashing.

When the success message appears, the firmware flashing is complete.

Install the flashing tool

This step is not required for FLY host boards.
If installation is needed, ensure the host board is connected to the internet.
If the flashing tool has already been installed, you can skip this step.

sudo apt update
sudo apt install dfu-util -y

Check the device connection status

Run the following command to confirm whether the device is successfully connected:

lsusb

If the DFU device is not recognized, try re-entering flashing mode.
On some system versions, the device name may differ. As long as 0483:df11 appears, it indicates that flashing mode has been successfully entered.

Obtain the precompiled firmware

Please download the firmware for the corresponding model from the Windows Flashing Tutorial tab at the top of this page, or from the "Firmware Flashing / Firmware Update" page of the corresponding product.

Flash the firmware

Tip

Only one firmware needs to be flashed

Below is the flashing command for 500K CAN baud rate firmware

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

Below is the flashing command for 1M CAN baud rate firmware

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

If the content File downloaded successfully appears as shown below, the flashing was successful

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Tip

After flashing is complete, the motherboard must be completely powered off once.

SHT36_V2 Katapult firmware
You can obtain the firmware via the following link:

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。

Firmware location:

FLY-Firmware/ToolBoard/SHT36

Power Off Operation

Before connecting or reconnecting the USB cable, fully shut down the printer and disconnect other power supplies. Do not allow the tool board to be powered simultaneously by the printer power supply and the USB interface.

Download and extract DFUProgrammer from the Auxiliary Software Download Page.
Manually install the APM32 DFU driver contained in the toolkit.
Save the firmware downloaded from this page to an easily accessible location on your computer.

Windows File Extension Display

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

After confirming the device has entered DFU flashing mode as per the product tutorial, connect it to the computer using a USB cable that supports data transfer.
Open DFUProgrammer, and select the device and firmware as shown in the figure below.

Click "Start Firmware Update" and wait for the progress to complete. Only after the success prompt appears, power off and restore the wiring according to the "Complete Flashing" requirements on this page.

Pull pre-compiled firmware
These are all pre-compiled firmware files
Please note that the host machine needs internet access to install
Please choose the appropriate download method based on your system

Linux System
FLYOS System

The host machine needs to execute the following command to download the firmware package

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

If the firmware package has already been downloaded, it is recommended to update it before proceeding with the remaining operations

cd ~/FLY-Firmware && git pull

On FLYOS, the firmware package is downloaded to /data/FLY-Firmware by default, and a symbolic link /root/FLY-Firmware is created. Subsequent flashing command paths are consistent with Linux.

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

If the firmware package has already been downloaded, it is recommended to update it before proceeding with the remaining operations

cd /data/FLY-Firmware && git pull

This method updates the existing Katapult firmware on the toolboard directly via CAN
Replace <Toolboard ID> with the CAN ID of the toolboard controlled by the STM32F103

Version Notes

Choose the correct command based on your system version:

FlyOS-FAST 1.3.8 and above or systems with Klipper updated after April 9, 2026:
103 version at 1M CAN baud rate:

~/klippy-env/bin/python ~/klipper/lib/katapult/flashtool.py -f ~/FLY-Firmware/developer/SHT36/FLY_SHT36V2_103_1M.BIN -u <Toolboard ID>

103 version at 500K CAN baud rate:

~/klippy-env/bin/python ~/klipper/lib/katapult/flashtool.py -f ~/FLY-Firmware/developer/SHT36/FLY_SHT36V2_103_500K.BIN -u <Toolboard ID>

Older system versions (before FAST 1.3.8 or systems without Klipper update before April 9, 2026):
072 version 500K CAN rate:

~/klippy-env/bin/python ~/klipper/lib/canboot/flash_can.py -f ~/FLY-Firmware/developer/SHT36/FLY_SHT36V2_103_500K.BIN -u <Toolboard ID>

Confirm whether the firmware has started

If the firmware starts normally, the LED will blink
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