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Glowbit Rainbow

On this page we will learn

  • how to connect the Glowbit Rainbow
  • how to set one LED's colour
  • how to fill and clear all the LEDs

Terminology

  • alligator clip – a spring-loaded metal clip on a wire used to make quick connections without soldering.
  • GND – ground, the connection that completes an electrical circuit back to the negative side of the power.
  • data pin – the pin that carries signals from the micro:bit to tell a device what to do.
  • NeoPixel – a type of full-colour LED that can be joined in strips and controlled one at a time from a single data pin.

The Glowbit Rainbow is an arc of 13 full-colour LEDs, each of which can be set to any colour.

Possible uses:

  • level meters for sound or sensor readings
  • countdown timers
  • decorative light effects
  • colour-coded status displays

Connect it

Unplug the micro:bit's USB cable and battery before wiring. Connect the Glowbit to the micro:bit with alligator clips:

  • black → micro:bit GND to Glowbit GND
  • red → micro:bit 3V to Glowbit 3V
  • yellow → micro:bit 0 to Glowbit Data

wiring diagram

The Glowbit uses MicroPython's built-in neopixel module, so no extra files are needed.

  • The LEDs are numbered 0 to 12.
  • Colours are tuples of three numbers, (red, green, blue), each from 0 to 255.
  • Changes only appear after show().

Set it up

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from microbit import *
import neopixel

rainbow = neopixel.NeoPixel(pin0, 13)

Methods

Method Parameters Returns Description
neopixel.NeoPixel(pin, n) pin: the data pin
n: number of LEDs		 NeoPixel Creates the LED strip
rainbow[n] = colour n: LED 0–12
colour: (r, g, b)		 none Sets one LED's colour
rainbow.fill(colour) colour: (r, g, b) none Sets every LED to one colour
rainbow.show() none none Sends the colours to the LEDs
rainbow.clear() none none Turns every LED off straight away

Setting one LED

Sets the colour of one LED by its number. The colour appears after show().

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from microbit import *
import neopixel

# Setup
rainbow = neopixel.NeoPixel(pin0, 13)

# Main loop
while True:
    rainbow[0] = (255, 0, 0)
    rainbow.show()

PRIMM

  1. Predict what you think will happen. Be specific.
  2. Run the program.
  3. Time to investigate the code. What does each line do?
Code explanation
  • line 1 → imports all the commands from the microbit library.
  • line 2 → imports the neopixel module.
  • line 5 → creates a strip of 13 LEDs on pin 0 and calls it rainbow.
  • line 8 → starts an endless loop.
  • line 9 → sets the first LED to red.
  • line 10 → sends the colours to the LEDs.

fill() and show()

fill() sets every LED to the same colour. show() sends the colours to the LEDs.

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from microbit import *
import neopixel

# Setup
rainbow = neopixel.NeoPixel(pin0, 13)

# Main loop
while True:
    rainbow.fill((0, 50, 0))
    rainbow.show()

PRIMM

  1. Predict what you think will happen. Be specific.
  2. Run the program.
  3. Time to investigate the code. What does each line do?
Code explanation
  • line 1 → imports all the commands from the microbit library.
  • line 2 → imports the neopixel module.
  • line 5 → creates a strip of 13 LEDs on pin 0 and calls it rainbow.
  • line 8 → starts an endless loop.
  • line 9 → sets every LED to a dim green.
  • line 10 → sends the colours to the LEDs.

clear()

Turns every LED off straight away.

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from microbit import *
import neopixel

# Setup
rainbow = neopixel.NeoPixel(pin0, 13)

# Main loop
while True:
    rainbow.fill((50, 0, 50))
    rainbow.show()
    sleep(1000)
    rainbow.clear()
    sleep(1000)

PRIMM

  1. Predict what you think will happen. Be specific.
  2. Run the program.
  3. Time to investigate the code. What does each line do?
Code explanation
  • line 1 → imports all the commands from the microbit library.
  • line 2 → imports the neopixel module.
  • line 5 → creates a strip of 13 LEDs on pin 0 and calls it rainbow.
  • line 8 → starts an endless loop.
  • line 9 → sets every LED to a dim purple.
  • line 10 → sends the colours to the LEDs.
  • line 11 → waits 1 second.
  • line 12 → turns every LED off.
  • line 13 → waits 1 second before the loop repeats.

Documentation

Documentation is the official guide written by the people who made the code library, and we can use it to look up every method and its parameters, including ones that aren't covered on this page.