CircuitPython

Doc Status Discord 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 Adafruit Blinka Library.

CircuitPython is based on below for differences. CircuitPython development is sponsored by Get CircuitPython

Official binaries for all supported boards are available through GitHub releases as well.

Documentation

Guides and videos are available through the CircuitPython category. An API reference is also available on Awesome CircuitPython.

Specifically useful documentation when starting out:

• CircuitPython Essentials
• Contributing

  See Code of Conduct. Contributors who follow the Discord too.

  Branding

  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 repo. This way we can update any custom code as we update the CircuitPython internals.
  • Your product is listed on 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.

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  Differences from Behavior

  • 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 (or settings.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 to boot_out.txt.
  • code.py (or main.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 from code.py in the REPL anymore. CircuitPython's goal for this change includes reduce confusion about pins and memory being used.
  • After code.py the REPL can be entered by pressing any key. It no longer shares state with code.py so 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.py or other main file after file system writes over USB mass storage. (Disable with samd.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

  API

  • Unified hardware APIs. Documented Modules
    • No module aliasing. (uos and utime are not available as os and time respectively.) Instead os, time, and random are CPython compatible.
    • New storage module which manages file system mounts. (Functionality from uos in MicroPython.)
    • Modules with a CPython counterpart, such as time, os and random, are strict CPython version. Therefore, code from CircuitPython is runnable on CPython but not necessarily the reverse.
    • tick count is available as Project Structure

      Here is an overview of the top-level source code directories.

      Core

      The core code of Ports

      Ports include the code unique to a microcontroller line and also variations based on the board.

      • atmel-samd Support for SAMD21 and SAMD51 based boards.
      • nrf Support for the nRF52840 based boards.
      • unix Support for UNIX. Only used for automated testing.

      The remaining port directories not listed above are in the repo to maintain compatibility with the back to top