Radio

Your micro:bit has a radio chip that can be used to transmit and receive messages.

Basic Functions

Getting ready

Before you can use the radio you must remember to import the radio library and to turn the radio on on. Once the radio is on it will hear the messages from any other micro:bit that is within range:

from microbit import *
import radio

radio.on()                      # Switch the radio on.

Setting a channel number

If you only want share messages within a group of devices then each micro:bit in the group must be configured to share the same channel number. The channel number must be a number between 0 and 100. You can do that like this:

radio.config(channel=19)        # Set the channel number to 19

It is important to do this if you are in a room with other people using their micro:bits because otherwise your micro:bit will overhear all the messages nearby and that is not what you want generally.

Setting the power level

Finally, you should set the power level for the radio, by default, your micro:bit will be transmitting on power level 0 which means that your messages might not get transmitted very far. The power level can be a value between 0 and 7:

radio.config(power=7)   # Set the power level to 7

Sending and receiving a message

Now you are ready to send or receive a message. You can send a string which is up to 250 characters in length in the message. Here is an example:

my_message = "We wish you a Merry Christmas and a Happy New Year."

radio.send(my_message)

Receiving a message is similar in nature, just use:

message_received = radio.receive()

Putting it together

Your micro:bit is smart, it can send and receive messages in quick succession. Just tell the micro:bit to keep checking for messages or sending them like this:

from microbit import *
import radio

radio.on()
radio.config(channel=19)        # Choose your own channel number
radio.config(power=7)           # Turn the signal up to full strength

my_message = "Be nice to yu turkeys dis christmas, Cos' turkeys just wanna hav fun, Turkeys are cool, turkeys are wicked, An every turkey has a Mum."

# Event loop.
while True:
        radio.send(my_message)
        incoming = radio.receive()
        if incoming is not None:
            display.show(incoming)
            print(incoming)
        sleep(500)

If you print the incoming message, you will see that sometimes it contains the value None. That is because sometimes the micro:bit checks for a message but nothing has arrived. We can ignore these non-events by checking whether incoming equals None and ignoring it if that is the case.

Exercises

1. Send a message every time button A is pressed. Send another message when B is pressed.
2. You will need a pair of micro:bits. Program one micro:bit to receive messages and print the message received using the print() method. Leave this micro:bit plugged into your computer with a USB cable. Program the other micro:bit to send accelerometer readings or the temperature readings in messages every second. Unplug this micro:bit and use a battery pack to power it. Congratulations! you have created a data logger!