BBC micro:bit V2 Sensor Reference Guide

⚠️ Temperature Sensor — Critical Calibration Issue

The temperature sensor reads the CPU die temperature, not ambient air temperature. It typically reads 3–8°C higher than the actual room temperature, and the offset varies by device and workload.

Classroom fix: Have students measure the offset by comparing the micro:bit reading to a known thermometer, then subtract the offset in code. This is a real engineering calibration exercise!

let offset = input.temperature() - KNOWN_ROOM_TEMP
basic.forever(function () {
    let calibrated = input.temperature() - offset
    basic.showNumber(calibrated)
})

Compass — Requires Calibration Dance

On first use, the micro:bit displays "TILT TO FILL SCREEN" — tilt the board to light up all LEDs. This calibrates the magnetometer. Nearby magnets, metal desks, and electronics can interfere.

Light Sensor — Uses the LEDs

The light sensor works by briefly reversing the LED matrix to sense ambient light. This means the display flickers very briefly during readings. In a dark room, readings may be inaccurate if the LEDs are actively displaying something bright.

Microphone — V2 Only

The built-in MEMS microphone is new in V2. It measures sound level (loudness), not frequency or pitch. Values are relative (0–255), not calibrated to actual decibels. Good for "loud vs. quiet" experiments, not precise acoustic measurement.