Small Basic + micro:bit

Today is a guest blog post from a 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