btkb

A bluetooth HID keyboard emulator service and FIFO client.

Goal

The purpose of this project was to create a way to relay messages to control an Amazon Firestick quickly (since it's for a TV remote). It's quite possible this isn't the fastest way, but it's certainly faster than using adb shell keyinput or sendevent.

I'm currently using this on a Raspberry Pi Zero W to dispatch commands received from IR signals on a TV remote. I went with the FIFO passthrough because the remote's protocol is DirecTV, and either I'm too stupid or lazy to figure out any other way to use it (ie. ir-keytable) than "raw codes" with LIRCD. Ultimately, the btkb command in this repo is used by irexec. This setup still allows for some IR codes to be "exchanged" - for example, specific buttons on a remote can lead to irexec emitting different IR codes for devices that have no other way to commmunicate. This story has little to do with the actual code here, but I hope you enjoyed it.

Setup

1. Get the repo

git clone git@github.com:maxakuru/btkb.git

2. Enable bluetooth if needed

sudo hciconfig hcio up

3. Copy config.ini.example and rename to config.ini

4. Configure config.ini how you like, at least the device address is needed

Note: To get the bluetooth device address, use sudo hciconfig hci0 -a and look for BD Address.

5. Run the setup script (or set it up however you want)

/bin/bash setup.sh

6. Pair your device

sudo /usr/bin/bluetoothctl

Then

agent on
default-agent
pairable on
discoverable on

And leave this terminal running.

Find your device in the bluetooth device list, pair, accept Back in the terminal, accept the pairing code with yes.

7. Send keystrokes via fifo A convenience script is installed with the setup script, but really it just pushes whatever the arguments you provide into a fifo. This fifo is then read, line by line, by the FifoClient, converted into HID bytestrings and sent to the connected device. The fifo is owned by uid/gid 1000, but depending on step 2, you may need sudo.

Sample commands

Press down "enter":

btkb KEY_ENTER

Press down "enter", release all keys:

btkb KEY_ENTER ACT_RELEASE

Press down "enter", hold it for a second, release:

btkb KEY_ENTER ACT_HOLD_1 ACT_RELEASE

Left ctrl + esc, then release keys and unhold "ctrl" modifier:

btkb MOD_LEFTCTRL KEY_ESC ACT_RELEASE MOD_RESET

Note: this works the same as the KEY_HOMESCREEN event on Firestick (and maybe other Android TV devices)

Alternative use

Write directly to the fifo, if you want:

echo "KEY_ENTER ACT_RELEASE" >> /tmp/btkb.fifo

Note: This requires using the same user as configured in config.ini

Credits

Not sure who this is, but very helpful!

AnesBenmerzoug/BluetoothHID