Small Basic + micro:bit

Today is a guest blog post from teacher, Jez Dean...

In this blog post: Build a computer-to-micro:bit connection with Small Basic.


You can write a simple GUI to send commands to a micro:bit running Python:

The program sends Python commands over a serial connection to the micro:bit. I've kept it as simple as possible so you can customize it further.

Clicking PIN0 High sends the command pin0.write_digital(1) to the micro:bit. You could type and click Send Command would show a smiley on the micro:bit.


  1. Flash a Python program to the micro:bit. You can just flash an empty program from within mu.
  2. Install the lit dev extensions for Small Basic. These are used to communicate over a serial connection.
  3. Find out the COM port of your microbit.
  4. Add your COM port at the top of the Small Basic code.


comPort = "COM4"


While ("True")

Sub Initialise
  'draw window'
  GraphicsWindow.Width = 500
  GraphicsWindow.Height = 100
  GraphicsWindow.Title = "Small Basic Microbit Controller"

  'draw pin control buttons'
  pin0high = Controls.AddButton("PIN0 High", 20, 10)
  pin0low = Controls.AddButton("PIN0 Low", 100, 10)

  'draw status and command buttons & boxes'
  statusbox = Controls.AddTextBox(20,50)
  value = Controls.AddTextBox(210,13)
  send = Controls.AddButton("Send Command", 380, 10)

  'Open connection to microbit'
  Controls.SetTextBoxText(statusbox,"Status : "+ LDCommPort.OpenPort(comPort, 9600))

  'Assign variables'
  Controls.ButtonClicked = OnButtonClicked
  nl = Text.GetCharacter(10) 'new line character'

Sub OnButtonClicked
  button = Controls.LastClickedButton
  val = Controls.GetTextBoxText(value)

  'if button pressed, send command and new line character'
  If (button = pin0high) Then
  ElseIf (button = pin0low) Then
  If (button = send) And (val <> "") Then

Adapted from litdev on the Small Basic blog


  • This is not interactive; it will not return any value the microbit sends.
  • This will only work over USB. Python does not work over Bluetooth.

See Also

Other Resources from Jez Dean

Comments (2)

  1. Thank you very much Jez Dean for sharing your blog.

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