SUT — Shimano UART Tool

SUT (Shimano UART Tool) is a Python tool for monitoring and analyzing Shimano e-bike UART traffic using a raspberry pi. It can capture messages from Shimano components (battery, motor, display) and optionally send test data via a named pipe.

Running the Tool

Make sure your uart0/serial0 is enabled, and raspberry pi bt is not using it.

systemctl is-enabled serial-getty@ttyAMA0.service
systemctl is-active serial-getty@ttyAMA0.service

should return

disabled
inactive

if not use

sudo raspi-config

and select

3. Interface Options
I6. Serial Port
=> Would you like a login shell to be accessible over serial
NO
=> Would you like the serial port hardware to be enabled
YES

/boot/firmware/config.txt

[all]
enable_uart=1
dtoverlay=disable-bt

Reboot after changes.

ls -l /dev/serial*

should return

/dev/serial0 -> ttyAMA0

Then you are good to go.

Activate your Python environment and start the tool:

./run.sh

Example output when starting:

Activating venv
Start tool

Press Ctrl+C to exit cleanly.

Sending Data via Pipe

SUT can send raw bytes to the bus using a named pipe. This is useful for testing or simulating messages.

The tool takes care of creating the named pipe, so make sure it is running.

Send a test message to the pipe:

echo -ne '\x00\x42\x00\x00\x00' > /tmp/sut_pipe

Expected tool output:

S: 00 42 00 91 7A
R: 00 C2 00 5D F6

S: — message sent to the bus
R: — message received from the bus

This acts as a simple sanity check to verify the tool is reading and sending messages correctly.

Loopback testing

If you want to make sure everything on the pi side is up and running you can do a loopback test.

Connect RX and TX on your pi together

Run the tool, pipe in the command as described above.

Expected tool output:

S: 00 42 00 91 7A
R: 00 42 00 91 7A

Please make sure to not include this loopback test in your logging data, either by manually removing it from the days data file, or disabling logging in config.json before starting the tool with:

{
    "logger": false
}

Colored Output

Color	Meaning
(normal)	Valid message received
Yellow	Incomplete message detected
Red	CRC error detected

Press Ctrl+C to exit.
The tool will cleanly close the serial port and any open pipes.

Notes

Requires Python 3.8+
CRC16 calculation and UART parsing are handled automatically
Currently only tested on BT_E6000