Code

Duration: ~15 minutes

Step 1: wire up the servo

Follow the instructions in servo 101 manual to connect the servo to the micro:bit.

Step 2: code light sensor

Code the lightsensor on the micro:bit to control the servo.

basic.forever(() => {
    led.plotBarGraph(
        input.lightLevel(),
        0
    )
    pins.servoWritePin(AnalogPin.P0, input.lightLevel())
})

It works but your servo might be trying to move too much. Let’s calibrate it.

Step 3: calibrate the servo

Download the servo calibration program to determine to opening and closing angles of the servo for your robot.

We are going to map the light level range, [0, 255] to the angle range, [closed, opened] using pins.map.

let angle = 0
let closed = 0
let opened = 0
basic.forever(() => {
    led.plotBarGraph(
        input.lightLevel(),
        0
    )
    angle = pins.map(
        input.lightLevel(),
        0,
        255,
        opened,
        closed
    )
    pins.servoWritePin(AnalogPin.P0, angle)
})
// TODO: use the angle found at calibration!
opened = 95
// TODO: use the angle found at calibration!
closed = 175