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JEJunior Engineer LabPico W + micro:bit course
04 25 minutes

Button light

The board starts listening instead of only talking

Button light project
Illustration of the finished idea. Build from the diagram and connection table, not the photo.

Mission goal: Read a pushbutton on GP15 with an internal pull-up resistor and make the GP16 LED follow it: pressed means lit.

Section 1

Understand

New ideas

  • Input pins versus output pins
  • What a pull-up resistor does
  • Why pressed reads 0 and released reads 1
  • The four-leg tactile button trap
  • 1A button is an input: the board listens instead of talks.
  • 2With pull-up, released reads 1 and pressed reads 0.
  • 3Use one leg from each internal pair of the button.

Safety first

  • Unplug the USB cable before you add the button.
  • Any continuity check with a multimeter is done with the board unplugged, by an adult.
  • Never wire the button between 3.3 V and ground with nothing else. That is a short circuit you can create by accident when hunting for legs.