Radio & Communication on BBC micro:bit

Radio on the micro:bit

The micro:bit has a 2.4 GHz radio (using the same hardware as Bluetooth) that can communicate directly with other micro:bits ߀” no router or internet required. This is perfect for classroom projects where multiple boards need to talk to each other.

The radio module in MicroPython gives you a simple broadcast API ߀” all boards on the same channel and group receive each other's messages.

Setting Up Radio

import radio
from microbit import *

radio.on()                    # Must call this before using radio
radio.config(channel=7)       # Channel 0߀“83 (default 7)
radio.config(group=1)         # Group 0߀“255 (default 0) ߀” only same group receives
radio.config(power=7)         # Transmit power 0߀“7 (default 6)

Sending a Message

import radio
from microbit import *

radio.on()

while True:
    if button_a.was_pressed():
        radio.send("hello")
        display.show(Image.ARROW_E)
        sleep(200)
        display.clear()

Receiving a Message

import radio
from microbit import *

radio.on()

while True:
    message = radio.receive()
    if message:
        display.scroll(message)
    sleep(100)

radio.receive() returns a string if a message is waiting, or None if not.

Two-way Communication

Both boards run the same code ߀” they can send and receive:

import radio
from microbit import *

radio.on()
radio.config(group=42)

while True:
    if button_a.was_pressed():
        radio.send("ping")
        display.show(Image.ARROW_E)
        sleep(200)

    msg = radio.receive()
    if msg == "ping":
        display.scroll("pong!")
        radio.send("pong")
    elif msg == "pong":
        display.show(Image.HAPPY)
        sleep(500)
        display.clear()
    sleep(50)

Sending Numbers and Data

Radio sends and receives strings. Convert other types explicitly:

# Sender
temp = temperature()
radio.send(str(temp))

# Receiver
msg = radio.receive()
if msg:
    value = int(msg)
    display.scroll(str(value) + "C")

For structured data, encode as CSV or simple key=value:

radio.send("temp=" + str(temperature()) + ",x=" + str(accelerometer.get_x()))

Radio Details

Parameter	Range	Default	Effect
channel	0߀“83	7	Frequency offset ߀” change to avoid interference
group	0߀“255	0	Logical group ߀” messages only received within same group
power	0߀“7	6	Transmit power (7 = maximum range ~70 m line-of-sight)
length	max bytes	32	Maximum message length

Bluetooth Overview

The micro:bit also supports Bluetooth Low Energy (BLE) for connecting to phones or tablets via the micro:bit iOS/Android app.

BLE on the micro:bit is primarily used through MakeCode Bluetooth extensions or via the official app. BLE and radio cannot be used simultaneously in MicroPython ߀” the radio module takes over the 2.4 GHz hardware.

Pairing with the micro:bit App

1. Download the "micro:bit" app from the App Store or Google Play
2. In MakeCode, add the Bluetooth extension
3. Use the "Bluetooth Event" blocks to handle connections
4. Pair via the app ߀” hold A+B+RESET together when prompted

UART Serial Communication

The micro:bit can also communicate with computers or other devices via UART (serial):

from microbit import uart

uart.init(baudrate=9600, tx=pin0, rx=pin1)

while True:
    if uart.any():
        data = uart.read()
        print("Received:", data)
    uart.write("Hello from micro:bit\r\n")
    sleep(1000)

I2C on the micro:bit

Connect I2C sensors to pin 19 (SCL) and pin 20 (SDA):

from microbit import i2c

devices = i2c.scan()
print([hex(d) for d in devices])

# Write to address 0x3C
i2c.write(0x3C, bytes([0x00, 0xAF]))

# Read 6 bytes from address 0x68
data = i2c.read(0x68, 6)