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Using a Push Button & Microbit
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How to use a tactile push button switch in microbit electronic projects
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jez
Use buttons to provide external inputs to the microbit.
external
Push Button
SMD push button switch by Sparkfun (CC-BY-2.0)
2016-12-23 10:20:00 UTC
2016-12-23 10:20:00 UTC

A small push button can be used to provide an external input into your circuits.

Push Button Diagram and Photograph{:.ui .image}

This is a small, SMD-mount tactile switch identical to the ones on your microbit. These switches are normally open (or NO) and so must be pushed to close the circuit. It said to be momentary as it must be held to close.

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Electronics

One of the button's pins is connected to 3V. The corresponding pin to pin0 of the microbit. When the button is pressed, pin0 reads True or 1.

Push Button Diagram and Photograph{:.ui .image .centered}

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Code

Python

Display a tick if button attached to PIN0 is pressed

{% highlight python %} from microbit import *

while True: # if pin1.read_digital() == 1 if pin1.read_digital(): display.show(Image.YES) else: display.show(Image.NO) sleep(10)

{% endhighlight %}

Experiment

  • Add multiple buttons
  • Count button presses. It'll be wrong; why?
Pull-down Resistor?

The microbit has internal pull-up and pull-down resistors. When a digital input is read by the microbit, the pull-down resistors are turned on so there is no need for an external one.

This behaviour can be modified in PXT but not Python.