| title | Light an external LED on the microbit bit |
|---|---|
| layout | text-width-sidebar |
| meta-description | Use electronics and breadboard to light a single LED with the micro:bit. |
| share | true |
| author | jez |
| about | Light a Single External LED. |
| cats | external |
| simple-description | LEDs |
| acknowledgements | Teaser image by Adafruit (CC-BY). |
| date | 2016-12-23 10:20:00 UTC |
| date-updated | 2016-12-23 10:20:00 UTC |
It's possible to use the external pins on the micro:bit to control external LEDs.
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Electric current can only flow one way through a light emitting diode (LED). It must flow through its anode (+) and out its cathode (-) to light.
The anode has a longer leg and often has a bend in it.
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A 220Ω resistor is added to reduce the voltage; without it the LED would blow.
{% include box.html content="which-resistor" %}
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{% highlight python %} from microbit import *
while True: pin0.write_digital(1) sleep(500) pin0.write_digital(0) sleep(500) {% endhighlight %}
{% highlight python %} from microbit import *
fade_amount = 5 # How much to change brightness each iteration speed = 10 # speed brightness changes brightness = 0
while True: brightness = brightness + fade_amount if (brightness <= 0) or (brightness >= 1023): fade_amount = -fade_amount else: pin0.write_analog(brightness) sleep(speed) {% endhighlight %}
Creates a lot of flickering in Python; not quite sure yet.
- Remove the resistor; what happens?
- Reverse the polarity of the LED; what happens?
- Make the LED flash when the button is pushed.