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BLE HID Keyboard

Overview

The BLE HID Keyboard sample demonstrates how to use the GATT Human Interface Device (HID) Service to implement a keyboard input device that you can connect to your computer.

This sample code enumerates the nRF52840 Connect Kit into a BLE HID keyboard that has an A key connected to the USER button.

Tip

adafruit_ble and adafruit_hid are pre-built into CircuitPython as frozen modules, so that they can be imported in the code directly.

Requirements

Before you start, check that you have the required hardware and software:

Running the code

To run the code, complete the following steps:

  1. Connect nRF52840 Connect Kit to your computer using the USB-C Cable.
  2. Start Mu Editor, click Load to open code.py in the CIRCUITPY drive.

  3. Copy and paste the following code into code.py and click Save:

    CIRCUITPY/code.py
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    import board
import digitalio

from adafruit_hid.keyboard import Keyboard
from adafruit_hid.keyboard_layout_us import KeyboardLayoutUS
from adafruit_hid.keycode import Keycode

import adafruit_ble
from adafruit_ble.advertising import Advertisement
from adafruit_ble.advertising.standard import ProvideServicesAdvertisement
from adafruit_ble.services.standard.hid import HIDService
from adafruit_ble.services.standard.device_info import DeviceInfoService

# USER button acts as A key on a keyboard
key_a = digitalio.DigitalInOut(board.USER)
key_a.direction = digitalio.Direction.INPUT
key_a.pull = digitalio.Pull.UP

# LED0 indicates A key is pressed
led = digitalio.DigitalInOut(board.LED0)
led.direction = digitalio.Direction.OUTPUT
led.value = True

# Use default HID descriptor
hid = HIDService()
device_info = DeviceInfoService(
    software_revision=adafruit_ble.__version__, manufacturer="Makerdiary"
)
ble = adafruit_ble.BLERadio()
ble.name = 'CIRCUITPY KEYBOARD'
advertisement = ProvideServicesAdvertisement(hid)
advertisement.complete_name = ble.name
advertisement.appearance = 961
scan_response = Advertisement()

if ble.connected:
    for c in ble.connections:
        c.disconnect()

print("advertising")
ble.start_advertising(advertisement, scan_response)

keyboard = Keyboard(hid.devices)

while True:
    while not ble.connected:
        pass
    while ble.connected:
        if not key_a.value:
            print("Key A pressed!")

            # Turn on LED0
            led.value = False

            while not key_a.value:
                pass    # Wait for key A released

            # Type keycode `Shift+A`
            keyboard.press(Keycode.SHIFT, Keycode.A)
            keyboard.release_all()

            # Turn off LED0
            led.value = True
    ble.start_advertising(advertisement)

  4. Your code will run as soon as the file is done saving. A Bluetooth keyboard with the name CIRCUITPY KEYBOARD can be discovered by your computer. Connect to the keyboard.

  5. Open a text editor and press USER button on the board. Every button press sends a character A to your computer, and this will be displayed in the text editor.