5. case 03 RGB led

5.1. Introduction


The RGB LED is a kind of LED which creates light of red, green and blue. In this case, we will let RGB LED flash in red, green and blue.

5.2. Hardware Connect


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  • Connect circuit as above picture and put 2 AAA batteries to batteries pack.

5.3. Principles of Circuits


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The GND of slot on micro:bit is into innards of batteries’ GND to generate current loop.

5.4. Introduction of Components


RGB LED

  • The RGB LED is an LED that has 3 integrated LEDs - red, green and blue in a single component which is divided into R, G and B channel. It is a well-known fact that red, green and blue are three primary colors of light. It can mix all color for everything. RGB LED can generate limitless types of color as well.

  • There are 2 types of RGB LEDs, common anode and common cathode. In common-cathode RGB LEDs, the common port connects to GND. While in common-anode RGB LEDs, the common port connects to VCC.

  • Our Experiment Box uses a common-cathode RGB LED.

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  • Note: Please note the positive and the negative when you are connecting.

5.5. Software


Step 1

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Step 2

  • Snap digital write pin into on button A pressed as below picture. Write 1 to the P0 port, 0 to the P1 port and 0 to the P2 port.

  • It means write 1 to R channel of the RGB and write 0 to G & b channel of the RGB.

  • RGB LED is the red light.

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  • Write code for the green light and the blue light in the same way.

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Program

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5.6. Result


  • When the button A be pressed, RGB LED emits red light.

  • When the button B be pressed, RGB LED emits green light.

  • When the button C be pressed, RGB LED emits blue light.

5.7. Think


  • What is the color be after mix of red and blue? Show it!

5.8. Questions


5.9. More Information