Micro:bit Lesson — Temperature and Light Sensors (MicroPython)

Objective

Students will read temperature (°C) and ambient light (0–255) from the BBC micro:bit and display values on the LED matrix.

What You’ll Learn

• Use temperature() to read Celsius temperature.
• Use display.read_light_level() to read ambient light (0–255).
• Store readings in variables and display them.
• Run continuous monitoring with while True:.

Challenge A — Reaction Display

• If light level < 60 → show a sad face.
• Else → show a happy face.

Copyfrom microbit import *

while True:
    light = display.read_light_level()
    if light < 60:
        display.show(Image.SAD)
    else:
        display.show(Image.HAPPY)
    sleep(400)

Challenge B — Temperature Warning

• If temp > 28 → flash “HOT!”.
• If temp < 18 → flash “COLD!”.

Copyfrom microbit import *

HOT = 28
COLD = 18

while True:
    t = temperature()
    if t > HOT:
        display.scroll("HOT!")
    elif t < COLD:
        display.scroll("COLD!")
    else:
        display.show("-")  # comfortable
    sleep(800)

Challenge C — Light-as-Dots

Map light level to a number of dots (0–5) and show that many pixels.

Copyfrom microbit import *

def dots(n):
    # build a simple left-to-right row image with n bright pixels (0–5)
    n = max(0, min(5, n))
    row = [9 if i < n else 0 for i in range(5)]
    return Image(":".join(
        ["".join(str(p) for p in row)] * 5
    ))

while True:
    lvl = display.read_light_level()       # 0..255
    count = int((lvl / 255) * 5 + 0.5)     # 0..5
    display.show(dots(count))
    sleep(350)

Extension Ideas

• Combine sensors: show HOT + DARK alert when t > 28 and light < 50.
• Log values to serial (use print()) and graph in Mu.
• Add A/B buttons to toggle between temperature and light views.