BLE HID coprocessor for microcontrollers

 

Teensy in green, ESP32-C3 in blue

I have a Teensy 4.1 operating as a Commodore 64 (and Vic-20, and 128, and Apple 1) emulator.  It already supports USB Host (via 5 pin header on top) and web page helper (via USB CDC).

The Teensy doesn't have wireless capability, but I wanted to add BLE keyboard support.  So enter the ESP32-C3 as a coprocessor.  It is running a custom firmware using the NimBLE library to enumerate BLE HID devices in pairing mode, and connects as soon as it finds one. If everything works successfully, it sends HID reports as ASCII over the UART channel (received at Teensy RX pin 0).  

While the Teensy is busy driving the LCD with a bunch of connections, the ESP32-C3 is only wired at 5V input, ground, and a TX pin.  The ESP firmware is built without USB CDC support so that the Serial line defaults to GPIO.  

Shown is a USB only ESP32-C3 board with the advantage of being slightly cheaper.  When I purchased it years ago when ESP32-C3 was relatively new, it was about US$2 on AliExpress.  Looking today, there's even more choices available in all sorts of price ranges and sizes.

So the Teensy is doing what it is good at, and the ESP32-C3 is filling in a wireless connection gap.  The red jumper is provided to be able to pull power.  Though the power connection does have its advantage that the ESP32-C3 has a USB-C port, while the Teensy has a USB-Micro connector.

Look Ma -- no wires!

Mouse, Trackpad, and Gamepad/Joystick are supported as well.  Gamepads and Joysticks will require HID maps which are loaded but not interpreted yet, nor passed on the interface (work to be done).  Joystick support is not implemented yet in my emulators, but stay tuned!