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Add an ability to choose the micro:bit port using environment variables

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bitio - A Micro:bit IO device

What is this?

bitio (pronounced bitty-o) is a micro:bit I/O library for Python. It allows you to run code in Python on a PC/Mac/Linux/Raspberry Pi and interact directly with the micro:bit. It works with both Python 2 and with Python 3 on Mac, PC, Raspberry Pi and Linux.

bitio logo

I gave a presentation at PyconUK 2017, which someone kindly recorded and uploaded to YouTube - here:

YouTube PyconUK 2017

NEWSFLASH - using with a V2.0 micro:bit or V1.5 micro:bit

The Python API's for sound and other touch features are still stabilising at present on V2. I hope to add more support for V2 when things are a bit more stable.

If you have a V1.5 micro:bit, a new sensor was fitted for the accelerometer and compass. This requires new hardware drivers in order to work.

You can get both a V1.5 and a V2 micro:bit to work by using the bitio.hex on the newarch branch here:

I am currently testing all the examples on this new branch, and will pull them back on to the main branch here when they pass there tests.

Where is the latest version?

The bitio library was written in part to support a new chapter to the highly successful childrens coding book 'Adventures in Minecraft'.

You can get the official version of the library that supports the book from here:

Official version - on Adventures in Minecraft site

If you want something a bit more leading edge with some experimental new features, go right to the author's website and get the latest code from here:

Development version - on whaleygeek site

What can I do with it?

This package is useful if you want to use the micro:bit as an input or an output device for other programs, e.g. for Minecraft. Tilt your micro:bit, and something happens in the Minecraft world. It can be used for anything though, where you want to use the input and output devices on the micro:bit inside a Python program on a bigger computer.

About the Micro:bit

About MicroPython

About Minecraft

Show me some projects!

Kevin Thomas from MyTechnoTalent, Washington DC, attended micro:bit Live 2020 and was signposted to bitio. He then went on to make some fantastic resources using bitio as a way to get internet connectivity.

ML with micro:bit

Josh from EduBlocks added bitio support, after we met at PyconUK 2017.

Edublocks and bitio

Mr NCSComputing (Chris Penn) has written up a lot of projects using bitio and minecraft together:

Bitio with Minecraft

Sean M. Tracey has written a NodeRed wrapper for it:


Giles Booth has built an internet controlled Radio with it:

Internet Radio

Dr Simon Monk wrote about BitIO in his new MicroPython book:

Dr Simon Monk

Musab Kılıç used with pyuserinput to build a motorbike simulator:


Muzaffer Yağız Yasak used with instructions from MicroBike and w10toast to build a reminder system:


And of course, David Whale added a chapter to the book Adventures in Minecraft all about micro:bit and it uses bitio:

Adventures in Minecraft

Getting Started

There are a number of ways you could get bitio installed, however this route is designed to be mostly 'install free', specifically to make it easy for schools to use the package where there is a mostly locked-down Python environment.

Press the green CODE button which shows a download icon


Unzip the zip file

Flash the bitio.hex file onto your micro:bit by dragging and dropping it onto the MICROBIT drive that appears when you plug in your micro:bit. The bitio logo will appear on the display to show you that it has loaded correctly.

The best way to use the package in a restricted school environment is to then just copy the 'microbit' folder into the students home folder. Any Python programs that they write and store in their home folder will now automatically find the 'microbit' package when they 'import microbit' from any of their Python programs.

If you are on Windows, you first need to install the mbed serial driver first before you can use the serial port on your micro:bit. You don't need to do this on Mac/Pi/Linux as they have a compatible driver already built into the OS. Note that you need admin access to your PC and the micro:bit must be plugged in when you install the driver for it to work (but it says that on the web page linked below)

For windows, follow these instructions:

How to install the Windows mbed serial driver

Making a connection

Run (in Python 2 or Python 3, both are supported) the example that is in the src folder.

You could run this from the command prompt if you know how. But it is also just as easy to open from within the IDLE editor and run it, and it should work fine.

Follow the on screen instructions which will walk you through unplugging and plugging back in the micro:bit, as a way to detect which serial port it is connected to on your computer.

warning:Could not open the serial port that was remembered from last time
Scanning for serial ports
remove micro:bit, then press ENTER
found 132 micro:bit(s)
plug in micro:bit, then press ENTER
found 133 micro:bit(s)
found 1 new micro:bit
Do you want this micro:bit to be remembered? (Y/N)y
Your micro:bit has been detected
Now running your program

You could also specify the connected port by setting the environment variable BITIO_PORT:

  • Windows set BITIO_PORT=COM7
  • GNU/Linux export BITIO_PORT=COM7

Finally, you should get a counter counting from 00 to 99 in the WhaleySans font (2x5 sized digits) on the display.


There are no official docs yet, but here is a short quick-reference to get you started. Note I have added a microbit.sleep(2000) at the end of some examples, because once your Python program finishes the bitio icon will be displayed on the micro:bit again and this will overwrite whatever is on the micro:bit screen.

Connecting to the micro:bit

    NOTE: Make sure bitio.hex is installed
    import microbit

Scrolling text on the screen

    import microbit

Displaying a single character

    import microbit"A")

Displaying numbers

    import microbit

Displaying numbers using a 2-digit font

    import microbit
    for n in range(99):

Getting a list of pre-defined images

    import microbit

Displaying a pre-defined image

    import microbit

Spinning a clock

    import microbit
    for c in microbit.Image.ALL_CLOCKS:

Defining a custom image

    import microbit
    BANANA = microbit.Image("00090:00090:00990:09900:99000")

Clearing the display

    import microbit

Sensing when a button is pressed

    import microbit
    while True:
        if microbit.button_a.was_pressed():

Sensing when a pin is touched

    import microbit
    while True:
        if microbit.pin0.is_touched():

Reading accelerometer values

    import microbit
    while True:

Sensing tilt in the X plane

    import microbit
    while True:
        x = microbit.accelerometer.get_x()
        x = abs(x)
        if x > 200:
            print("Not Tilted")

Reading the temperature

    import microbit
    while True:  

Using the radio

(see also example).

Thanks to @jarvisteach for this contribution.

    import microbit, queue=10)

    while True:
        incoming =

        if incoming != "None":  #TODO: will need better None handler.
            incoming = stripMakeCodeHeader(incoming)


These items are currently not implemented in this release, but will be added soon.

pin[3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20] digital_read() digital_write() analog_read() analog_write() set_pull()

display get_pixel(x, y) set_pixel(x, y, value) on() off() is_on()

Sample programs

Here are a few sample programs you can use to get started  - sense a button press - count from 00 to 99 - sense buttons and accelerometer values - sense pin touch - use in-built standard images - define your own custom images - show how to sense tilt movements - use the tilt with Minecraft - show a spinning clock - show a spinning arrow - receive messages from a radio and log to a file (contributed)

Not all of the features of the micro:bit are made available via this API yet, but we're working on it!


The bitio code that runs at the micro:bit end is MicroPython. The version of MicroPython cached inside this project is from here:


Historical Perspective and timeline

On 9th May 2014 I published a package called 'anyio'. This was as a result of developing a coding book called Adventures in Minecraft, and the desire to add some hardware chapters. At the time, there wasn't a credible off the shelf GPIO like platform that worked out of the box, for PC/Mac/Linux. So I created something a bit like RPi.GPIO but called it anyio, so that it was possible to write Adventure 5, 9 and 10 of the book with minimal changes between all platforms. Some work was done by SKPangUK as a local distributor, who 'finishes off' the board by soldering headers and pre-loading the anyio firmware, as well as selling a bundled package with everything you need to follow the book.

Another key innovation inside anyio is the portscan package that I wrote. This works on PC/Mac/Linux/Raspberry Pi and walks the user through a workflow of removing and inserting the USB cable as a simple method to self-identify the port. This was key to reducing the size of the setup instructions inside the 'Adventures in Minecraft' book, as it makes the workflow identical on all 4 platforms. I have since used this workflow and package in lots of my other example micro:bit programs inside my github code repository.


skpang anyio

On 28th Jan 2016, I wrote a proof-of-concept in a project called 'mb_remote', which is here:


This was built using an older version of MicroPython, and the API has changed since. I spoke to a number of people that attended PyCon UK that year, and raised some interest.

This spawned similar work, e.g. this from Joe Glancy and Andrew Mulholland published on 9th May 2016 here:


Much as I like this work, I never agreed with the name. The main reason is that I wanted it to be possible to take an unmodified program written for the micro:bit, run it on a PC/Mac/Linux/Raspberry Pi machine, and for it to work unmodified. Hence the module name needs to be called 'microbit'.

Also, you will note that microperi requires manual connection to the micro:bit, whereas bitio automatically connects when you import the module.

There are many places where I have used this, but the most recent is a 'micro:bit radio gateway' project here:

radio gateway

In May 2016, I had discussions with Ryan Walmsley from Ryantek, and he wanted to build a board a bit like my anyio board but with Raspberry Pi HAT headers on it, and he asked for permissions to use my anyio library as a basis, which I agreed to. Ryan ran a successful kickstarter and ended up building a retail packaged board with support for I2C, SPI, and many of the boards in the huge Raspberry Pi HAT eco-system.

RTk.GPIO board

Roll forward to 2017, and discussions start to take place between myself and my co-author Martin O'Hanlon about developing a 2nd edition of our highly successful childrens coding book 'Adventures in Minecraft'. I had this idea that now that the micro:bit is widely deployed and you can walk into real shops and buy them off of the shelf, it would be a much easier to obtain platform than the Arduino/anyio board, and also provide progression in both directions between Python on the micro:bit and Python on larger platforms.

Note a very influential (private) discussion with Nicholas Tollervy of the Python Software Foundation, where he states that 'using Raw REPL would be a more robust protocol for driving this sort of interface'. bitio uses the Raw REPL extensively.

raw REPL

So, bitio is a step towards using the micro:bit as a general purpose IO device for bigger computers like PC/Mac/Linux. You can of course also use it on the Raspberry Pi in addition or instead of RPi.GPIO, but you get some lovely on-board sensors and a display built-in with the micro:bit.

What is next?

I have a big todo list (look in the docs folder).

One key thing I want to do is to pull all my various micro:bit comms projects into this single package, including bringing in the microbit-gateway project for linking via the micro:bit radio network, amongst other features.

I also have a microbit.GPIO idea in the making, where it could be used a bit like RPi.GPIO and form part of my anyio package as another supported platform.

David Whale


5th September 2020


A micro:bit I/O device library for Python







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