This project was born out of curiosity and a certain aversion to buying a Bluetooth keyboard that will sit and collect dust most of the time.
It was also a project to explore how does Swift UI fare on Mac OS (spoiler: quite good, but not without its' problems) and to to work with custom-defined BLE interaction protocol.
- Client for macOS that sends keypresses to Arduino Nano 33 BLE
- Firmware for Arduino Nano 33 BLE that takes the data sent by client and emulates keypresses as a Human Interface Device
BLE specifications in this firmware are pretty simple:
- Device advertises itself with the name
Virtual Keyboard - Service
98ADis advertised - let's refer to it as keyboard service - Characteristic
98AFis a part of keyboard service. It can only be written to without confirmation. Let's refer to it as RX characteristic. - On every write to RX characteristic, a keypress will be generated based on the data written.
- Size: 32 bits
- First 16 bits are for HID key code (the key itself) as an unsigned integer
- Second 16 bits are for HID key modifier (Shift, Ctrl, etc.) as an unsigned integer
- Integers should be big-endian
It's not intended to be used as a keyboard replacement for something serious - if you need a keyboard, just go and buy one. This is mostly for fun and to see what interesting things could be squeezed out of Arduino.
- Sending input while screen is locked will lock up the device, leading to BLE connection loss sometimes.