This repository is an example on how to control a Signal K boat computer system using a cheap Bluetooth "camera shutter" button. Use case is starting the anchor alarm more conveniently:
- Single button click to set anchor and start watch
- Double click to stop anchor watch
- Raspberry Pi 3B+ running Signal K on Raspbian
- Bluetooth camera button (I'm using this model)
Set the camera button On.
SSH to your Raspberry Pi and discover the device:
$ hcitool scan
Scanning ...
XX:XX:XX:XX:XX:XX Camkix Shutter
Note down the Bluetooth ID shown for the button (the name and model may be different depending what button you bought).
Then pair and trust the button as a "Bluetooth keyboard":
$ sudo bluetoothctl
[bluetooth]# pair XX:XX:XX:XX:XX:XX
[bluetooth]# connect XX:XX:XX:XX:XX:XX
[Camkix Shutter]# trust XX:XX:XX:XX:XX:XX
Now you can run udevadm to see the device connection and disconnection events when turning it on and off:
$ udevadm monitor --environment
KERNEL[7000.708383] add /devices/platform/soc/xxxxxxxx.serial/tty/ttyAMA0/hci0/hci0:11 (bluetooth)
ACTION=add
DEVPATH=/devices/platform/soc/xxxxxxxx.serial/tty/ttyAMA0/hci0/hci0:11
SUBSYSTEM=bluetooth
DEVTYPE=link
SEQNUM=1358
...
Please note that this repository will not work for your hardware out of the box. You will need to adapt at least the udev and systemd files to match your hardware identifiers.
Clone this repository to /home/pi/kbd and adapt the files to your liking.
Note: You need to add your device ID to the listener.py file.
Install the dependencies with:
$ pip3 install -r requirements.pip
Copy the systemd service file in place and reload:
$ sudo cp systemd/signalk-bluetooth-button.service /etc/systemd/system
$ sudo systemctl daemon-reload
Copy the udev rules in place and reload udev:
$ sudo cp udev/99-camerabutton.rules /etc/udev/rules.d/
$ sudo service udev restart
$ sudo udevadm trigger
Now you should see the Python script starting and running whenever the Bluetooth button is turned on:
$ journalctl -u signalk-bluetooth-button -f
Mar 04 12:02:23 curiosity-pi systemd[1]: Starting Listen to Bluetooth camera button events...
Mar 04 12:02:24 curiosity-pi listener.py[1356]: Connected to button
Mar 04 12:02:27 curiosity-pi listener.py[1356]: Click, drop anchor
Mar 04 12:02:28 curiosity-pi listener.py[1356]: ok
Mar 04 12:03:46 curiosity-pi listener.py[1356]: Double click, raise anchor
Mar 04 12:03:46 curiosity-pi listener.py[1356]: ok
Mar 04 12:04:51 curiosity-pi listener.py[1356]: Disconnected
Mar 04 12:04:51 curiosity-pi systemd[1]: signalk-bluetooth-button.service: Succeeded.