This page describes MicroPython support since Thonny 3.2. See the bottom of the page for historical notes.
Before continuing, make sure that you have your device attached to a USB port. If required, install the necessary drivers for serial communication.
In Thonny, open the back-end manager (Run → Select interpreter) and choose the type of your device from the drop-down list. If your device doesn't have a specific back-end, then try "MicroPython (generic)".
Now you can specify the port your device is connected to. If you have only one board connected, then you could leave this setting for automatic detection.
After you press "OK", Thonny's shell should present either the prompt of your device's REPL or the output of the script which is currently running on your device.
(If you don't have suitable MicroPython (or CircuitPython) firmware installed on your device yet, then see below for the section about firmware installation.)
When you have a MicroPython back-end selected, "File => Open" allows you to open a file either from local disk, device's USB drive, or "directly" form your device's file system. Same goes to save commands ("Save", "Save as", "Save copy as").
Note that Thonny always synchronizes file writes — this reduces the risk of corrupt files when you accidentally reset your device without proper eject right after saving a file onto its USB drive.
You can also open files by double-clicking them in Thonny's file browser (View => Files).
During editing your scripts, Thonny offers autocomplete (performed by the jedi library). This is based on the API-s scraped from specific devices with specific MicroPython / CircuitPython versions (different for each backend type). This means that if you are using a different version of firmware then the autocompleter may offer some names that are not present on your device and miss some that are.
Although Thonny allows you to work without saving anything locally, for serious work we recommend keeping master copies of your scripts in your main computer (preferably under version control) and copy them to the device as required (File => Save copy as). It is too easy to lose your work if you rely only on the device's flash memory.
The easiest way to test your script is to execute it like you would with the CPython back-end — "Run → Run current script (F5)". It doesn't matter whether your script is stored on the local disk or on the device — in both ways Thonny simply submits the program text to device's REPL.
When you have saved your script onto the device (eg. as "main.py"), you can check how your device would perform without Thonny. This can be done easily by selecting "Run => Send EOF / Soft reboot (Ctrl+D)".
You can upload / download data and library files and directories via respective commands in the file browser (View => Files) menu (≡) or files' context menu (opened by right-clicking on a file).
After connecting to your device, Thonny switches it to raw REPL mode and uses this mode under the hood to run the scripts, query global variables, etc. For the user it is still presented as regular REPL. (Note that this mode change is not permanent — if you reset the device and open it with another program, REPL is back in regular mode. If you don't want to reset it then you can get back to regular mode with Ctrl+B.)
Because of using raw REPL under the hood, Thonny doesn't support Ctrl-A and Ctrl-B for switching between raw and regular REPL. It also doesn't support Ctrl-E for entering paste mode -- this is not necessary as you can paste any amount of code into the regular Thonny REPL.
Some MicroPython back-ends offer support for installing MicroPython to your device. In this case the back-end configuration page (Run => Select interpreter) has a button for this.
- MicroPython support in Thonny started with BBC micro:bit plug-in by Kauri Raba.
- General MicroPython support appeared in Thonny 3.0 and was meant to be used via separate plug-ins.
- Initially one had to edit scripts as local files and save them to the device with special commands in "Device" menu (as described here).
- Thonny 3.2 introduced device file browser and allowed to edit files directly in device's file system. "Device" menu was deprecated as file handling commands moved to file browser and firmware commands moved to respective back-end configuration pages. Upload commands are substituted with "File => Save as" and "File => Save copy as" commands.
- Thonny 3.2 incorporated several plug-ins (microbit, circuitpython, esp) into the main "thonny" package.