Connect

Use the radio to send the current moisture level to a dashboard micro:bit. The dashboard will display one LED per micro:bit.

Moisture sensor

To make it happen, we need to change the program to:

• setup the radio by choosing group 4 and sending the serial number of the device
• send the moisture level divided by 4 as the dashboard takes values between 0 and 255.

radio.setTransmitSerialNumber(true)
radio.setGroup(4)
led.setBrightness(64)
let reading = 0
basic.forever(() => {
    pins.analogWritePin(AnalogPin.P1, 1023)
    reading = pins.analogReadPin(AnalogPin.P0)
    radio.sendNumber(reading / 4);
    pins.analogWritePin(AnalogPin.P1, 0)
    led.plotBarGraph(
        reading,
        1023
    )
    if (input.buttonIsPressed(Button.A)) {
        basic.showNumber(reading)
    }
    basic.pause(5000);
})

The dashboard

The dashboard code is found in the radio dashboard example.

Setup a dashboard micro:bit

Download the code from that example into the micro:bit that will be used to display the results.

Dashboard operation

When the dashboard receives a message from a micro:bit, it finds a pixel to use for that board (and remembers it). The number sent in the messages from the board are used to set the brightness of the LED.

When a message hasn’t been received by the dashboard for awhile, it’s pixel will start to blink. Then, after some time, it will simply turn off.

radio