circuitpython.org | Get CircuitPython | Documentation | Contributing | Branding | Differences from Micropython | Project Structure
CircuitPython is a beginner friendly, open source version of Python for tiny, inexpensive
computers called microcontrollers. Microcontrollers are the brains of many electronics including a
wide variety of development boards used to build hobby projects and prototypes. CircuitPython in
electronics is one of the best ways to learn to code because it connects code to reality. Simply
install CircuitPython on a supported board via drag and drop and then edit a code.py file on
the CIRCUITPY drive. The code will automatically reload. No software installs are needed besides a
text editor (we recommend Mu for beginners.)
CircuitPython features unified Python core APIs and a growing list of 150+ device libraries and drivers that work with it. These libraries also work on single board computers with regular Python via the Adafruit Blinka Library.
CircuitPython is based on MicroPython. See below for differences. CircuitPython development is sponsored by Adafruit and is available on their educational development boards. Please support both MicroPython and Adafruit.
Official binaries for all supported boards are available through circuitpython.org/downloads. The site includes stable, unstable and continuous builds. Full release notes and assets are available through GitHub releases as well.
Guides and videos are available through the Adafruit Learning System under the CircuitPython category. An API reference is also available on Read the Docs. A collection of awesome resources can be found at Awesome CircuitPython.
Specifically useful documentation when starting out:
See CONTRIBUTING.md for full guidelines but please be aware that by contributing to this project you are agreeing to the Code of Conduct. Contributors who follow the Code of Conduct are welcome to submit pull requests and they will be promptly reviewed by project admins. Please join the Discord too.
While we are happy to see CircuitPython forked and modified, we'd appreciate it if forked releases not use the name "CircuitPython" or the Blinka logo. "CircuitPython" means something special to us and those who learn about it. As a result, we'd like to make sure products referring to it meet a common set of requirements.
If you'd like to use the term "CircuitPython" and Blinka for your product here is what we ask:
- Your product is supported by the primary "adafruit/circuitpython" repo. This way we can update any custom code as we update the CircuitPython internals.
- Your product is listed on circuitpython.org (source here). This is to ensure that a user of your product can always download the latest version of CircuitPython from the standard place.
- Your product has a user accessible USB plug which appears as a CIRCUITPY drive when plugged in.
If you choose not to meet these requirements, then we ask you call your version of CircuitPython something else (for example, SuperDuperPython) and not use the Blinka logo. You can say it is "CircuitPython-compatible" if most CircuitPython drivers will work with it.
Differences from MicroPython
CircuitPython:
- includes ports for MicroChip SAMD21 (Commonly known as M0 in Adafruit product names) and SAMD51 (M4).
- supports only SAMD21, SAMD51, and nRF52840 ports.
- tracks MicroPython's releases (not master).
- floats (aka decimals) are enabled for all builds.
- error messages are translated into 10+ languages.
- does not support concurrency within Python (including interrupts and threading). Some concurrency is achieved with native modules for tasks that require it such as audio file playback.
- The order that files are run and the state that is shared between them. CircuitPython's goal is to clarify the role of each file and make each file independent from each other.
boot.py(orsettings.py) runs only once on start up before USB is initialized. This lays the ground work for configuring USB at startup rather than it being fixed. Since serial is not available, output is written toboot_out.txt.code.py(ormain.py) is run after every reload until it finishes or is interrupted. After it is done running, the vm and hardware is reinitialized. This means you cannot read state fromcode.pyin the REPL anymore. CircuitPython's goal for this change includes reduce confusion about pins and memory being used.- After
code.pythe REPL can be entered by pressing any key. It no longer shares state withcode.pyso it is a fresh vm. - Autoreload state will be maintained across reload.
- Adds a safe mode that does not run user code after a hard crash or brown out. The hope is that this will make it easier to fix code that causes nasty crashes by making it available through mass storage after the crash. A reset (the button) is needed after its fixed to get back into normal mode.
- RGB status LED indicating CircuitPython state, and errors through a sequence of colored flashes.
- Re-runs
code.pyor other main file after file system writes over USB mass storage. (Disable withsamd.disable_autoreload()) - Entering the REPL after the main code is finished requires a key press which enters the REPL and disables autoreload.
- Main is one of these:
code.txt,code.py,main.py,main.txt - Boot is one of these:
settings.txt,settings.py,boot.py,boot.txt
- Unified hardware APIs. Documented on ReadTheDocs.
- API docs are rST within the C files in
shared-bindings. - No
machineAPI.
- No module aliasing. (
uosandutimeare not available asosandtimerespectively.) Insteados,time, andrandomare CPython compatible. - New
storagemodule which manages file system mounts. (Functionality fromuosin MicroPython.) - Modules with a CPython counterpart, such as
time,osandrandom, are strict subsets of their CPython version. Therefore, code from CircuitPython is runnable on CPython but not necessarily the reverse. - tick count is available as time.monotonic()
Here is an overview of the top-level source code directories.
The core code of MicroPython is shared amongst ports including CircuitPython:
docsHigh level user documentation in Sphinx reStructuredText format.driversExternal device drivers written in Python.examplesA few example Python scripts.extmodShared C code used in multiple ports' modules.libShared core C code including externally developed libraries such as FATFS.logoThe CircuitPython logo.mpy-crossA cross compiler that converts Python files to byte code prior to being run in MicroPython. Useful for reducing library size.pyCore Python implementation, including compiler, runtime, and core library.shared-bindingsShared definition of Python modules, their docs and backing C APIs. Ports must implement the C API to support the corresponding module.shared-moduleShared implementation of Python modules that may be based oncommon-hal.testsTest framework and test scripts.toolsVarious tools, including the pyboard.py module.
Ports include the code unique to a microcontroller line and also variations based on the board.
atmel-samdSupport for SAMD21 and SAMD51 based boards.nrfSupport for the nRF52840 based boards.unixSupport for UNIX. Only used for automated testing.
The remaining port directories not listed above are in the repo to maintain compatibility with the MicroPython parent project.