How to Use Programmable Buttons with Micro:bit?

( 1 )Project Description:
 

Buttons can be used to control circuits. In an integrated circuit with a button, the circuit is connected when pressing the button and it is open the other way around.

Micro: Bit main board V2 boasts three buttons, two are programmable buttons(marked with A and B), and the one on the other side is a reset button. By pressing the two programmable buttons can input three different signals. We can press button A or B alone or press them together and the LED dot matrix shows A,B and AB respectively. Let’s get started.

( 2 )Components Needed:
 

• Micro:bit main board V2 *1

• Micro USB cable*1

( 3 )Test Code 1：
 

Link computer with micro:bit board by micro USB cable, and program in MakeCode editor.

Delete“on start”and“forever”firstly，then click“Input”→“on button A pressed”

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Click“Basic”→“show string”;

Then place it into“on button A pressed”block, change “Hello!”into“A”.

Copy code stringonce, tap the drop-down button“A”to select“B”and modify character“A”into“B”.

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Copyonce，and set to“on button A+B pressed”and“show string “AB”

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Complete Code:

Select“JavaScript” and“Python”to switch into JavaScript and Python language code:

( 4 )Test Results 1：

After uploading test code 1 to micro:bit main board V2 and powering the main board via the USB cable, the 5*5 LED dot matrix shows A if button A is pressed, B if button B pressed, and AB if button A and B pressed together.

( 5 ) Test Code 2：
 

Click“Led”→“more”→“led enable false”,

Put it into the block“on start”，click drop-down triangle button to select“true” .

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Tap“Variables”→“Make a Variable…”→“New variable name：”

Enter“item”in the dialog box and click“OK”，then variable“item”is produced. And move“set item to 0”into“on start”block

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Click“Input”→“on button A pressed”.

Go to“Variables”→“ change item by 1 ”

Place it into“on button A pressed”and 1 is modified into 5.

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Duplicatecode string once，click the drop-down button to select“B”，then set“change item by -5”.

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Enter“Led”→“plot bar graph of 0 up to 0”

Keep it into“forever”block

Go to“Variables”to move“item”into 0 box，change 0 into 25.

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Go to“Logic”to move out “if…true…then…”and “=”blocks.

Keep“=”into“true”box and set to “>”.

Select“item”in the“Variables”and lay it down at left box of “>”，change 0 into 25；

D. Enter“Variables”to drag“set item to 0”block into“if…true..then…”, alter 0 into 25.

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Replicate code stringonce.

“>” is modified into “<” and 25 is changed into 0, leave it beneath code string.

Complete Program：

Select“JavaScript” and“Python”to switch into JavaScript and Python language code:

( 6 )Test Results 2：
 

After uploading test code 2 to micro:bit main board V2 and powering the main board via the USB cable, when pressing the button A the LEDs turning red increase while when pressing the button B the LEDs turning red reduce.