Voting Machine

In this project, a voter program is loaded onto a player’s micro:bit. The player uses the buttons to vote eitheryes or no and the vote is sent to a dashboard micro:bit using the radio. The dashboard allocates one LED per player and turns it on or off based on the vote.

The voter program

Assuming button A is for a NO vote and B is for YES, the voter program works like this:

Transmit a NO vote

When button A is pressed, a number 0 is sent via radio and the X symbol is shown on the screen.

input.onButtonPressed(Button.A, () => {
    radio.sendNumber(0)
    basic.showIcon(IconNames.No)
})

Transmit a YES vote

When button B is pressed, a number 255 is sent via radio and the Y symbol is shown on the screen.

input.onButtonPressed(Button.B, () => {
    radio.sendNumber(255)
    basic.showIcon(IconNames.Yes)
})

Set device serial number

In order to track the votes, we tell the radio to also transmit the device serial number.

radio.setTransmitSerialNumber(true)

Set the radio group

We arbitrarily choose 4 as the group used for the communications.

radio.setGroup(4)

Putting all the parts together, here’s the complete voter program:

input.onButtonPressed(Button.A, () => {
    radio.sendNumber(0)
    basic.showIcon(IconNames.No)
})
input.onButtonPressed(Button.B, () => {
    radio.sendNumber(255)
    basic.showIcon(IconNames.Yes)
})
radio.setGroup(4)
radio.setTransmitSerialNumber(true)
basic.showIcon(IconNames.Ghost)

The dashboard

The dashboard code is in the radio dashboard example.

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

When the dashboard receives a message from a micro:bit, it find a pixel for that board (and remembers it) and uses the number received as the brightness of the LED.

When a message hasn’t been received by a board for some time, it’s pixel will start to blink. After more time, it will simply turn off.

radio