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Case 5: Adjustable light ring

Introduction:​

Use the rotary encoder to control the brightness of the light ring, and set the color of the light ring through the "A" or "B" button of the micro:bit.

Purpose of the case:​

  1. Understand the rotary encoder and its working principle.

  2. Understand the rotary encoder programming building blocks in MakeCode.

Materials required:​

ItemPictureQuantity
micro:bit V21
Jacdac expansion board1
Jacdac 10cm connection wire2
Knob Encoder1
Light Ring1
USB Cable1

Sensor principle description:​

Principle description:

Rotary encoder: A sensor used to detect the direction and value of rotational motion.

Principle description:

Light ring: a circular light ring composed of 8 RGB lights.

Connection diagram​

As shown in the figure below, insert the micro:bit into the Jacdac expansion board, and use the connecting wire to connect the rotary encoder sensor and the light ring in a star shape to the gold finger interface of the Jacdac expansion board.

Programming software​

Microsoft Makecode

Makecode programming​

Step 1: How to add Jacdac extension​

  1. Enter Microsoft Makecode and click "New Project".

  1. In the pop-up window, enter a project name and click Create.

  1. Click "Extend" in the code drawer.

  1. In the pop-up interface, enter "Jacdac" and click the search icon, select the Jacdac software library, as shown in the figure.

Step 2:​

  1. Connect micro:bit to the computer with a data cable.

Note: If the micro:bit is running the Jacdac program for the first time, please pre-install a blank Jacdac program on the motherboard, otherwise skip this step.

  1. Connect the sensor, MakeCode will automatically identify and simulate it, and the sensor will provide real-time feedback of the sensor status in the simulation area.

  1. Click on "ADD BLOCKS" sensor expansion module.

    Note: To connect a new sensor, repeat the "Click on "ADD BLOCKS" sensor expansion module" operation process.

Write the program as shown​

https://makecode.microbit.org/_XcUA7T3VAAM8

You can also download the program directly from the following webpage, and start running the program after downloading.

Result​

Use the knob encoder to adjust the brightness of the light ring, and press the micro:bit motherboard buttons A and B to switch the color of the light ring.

Thinking​

How to switch more colors of the light ring using the micro:bit buttons A and B。