CircuitPython 5.0.0 Release Candidate 0! — @adafruit @circuitpython

This is a 5.0.0 Release Candidate — please test

This is release 5.0.0-rc.0 (Release candidate 0). If this release does not have show-stopper issues, it will be re-released as 5.0.0, the first 5.x.x stable release.

If you find a bug please check the current known issues and file an issue if something isn’t already known.


5.0.0 is the latest major revision of CircuitPython. It features many improvements and enhancements to displayio, including grayscale OLED and e-paper displays, extensive additions and improvements to BLE support, support for the STM32F4, iMX RT10xx and Sony Spresense microcontroller families, and PWM audio support.

Download from

Downloads are available from! The site makes it easy to select the correct file and language for your board. The downloads page is here.


To install follow the instructions in our new Welcome to CircuitPython! guide. To install the latest libraries, see this page in that guide.

Try the latest version of the Mu editor for creating and editing your CircuitPython programs and for easy access to the CircuitPython serial connection (the REPL).

New Features, Updates, and Fixes since 5.0.0 Beta 5


  • Speed up heap allocation by tracking first free chunk for multiple block sizes. Thanks @tannewt.
  • Fix crash after empty REPL session. Thanks @tannewt.
  • Fix MacOS crash when Mac wakes up with an ejected CIRCUITPY. Thanks @tannewt.
  • Added draft implementation of eveL, the Gameduino low-level bindings. Thanks @jamesbowman.
  • Allow storage.remount() to work even if MSC is disabled. Thanks @bmeisels.
  • time.monotonic_ns() is now accurate to microseconds. time.sleep() now rounds to the nearest millisecond. Thanks @dhalbert.
  • Include filename in “No such file/directory” error messages. Thanks @dhalbert.
  • Fix os.stat() integer overflow on non-longint builds. Thanks @dhalbert.
  • Implement to_bytes(..., signed=True). Thanks @dhalbert.
  • Support echoing of Unicode characters in REPL. Thanks @DavePutz.
  • Add RTS/CTS and RS485 capabilities to busio.UART. Thanks @mubes.


  • Update rotation so 0 is the default, making OnDiskBitmap much faster. Thanks @ladyada.
  • Allow tuple or list for displayio.Palette color. Thanks @dhalbert.
  • Fix OnDiskBitmap documentation. Thanks @makermelissa.

    nRF and BLE

  • Add cached buffer on heap for nRF neopixel_write. Thanks @rhooper and @dhalbert.
  • Add nRF SPIM3 support, allowing 32MHz SPI. Thanks @dhalbert.
  • Fix using too-small SPI transactions on nRF. Thanks @dhalbert.
  • Correct I2C frequency setting on nRF. Thanks @dhalbert.
  • Enable _bleio singleton Adapter when _bleio is imported. Thanks @dhalbert.
  • Disable experimental BLE file editing service for now. Thanks @tannewt.
  • Improve BLE error messages. Thanks @tannewt.


  • Add core temperature and voltage for STM32. Thanks @hierophect.


  • Fix SPI clock speed on iMX. Thanks @mubes.
  • Fix i.MX UART initialization. Thanks @mubes.
  • Enable displayio for mimxrt10xx boards. Thanks @arturo182.
  • Add directly loadable image support for i.MX. Thanks @mubes.

    Other board-specific fixes

  • Fix Arduino MKR Zero USB VID. Thanks @fgallaire.
  • Add additional pin definitions for OHS2020 board. Thanks @pdp7.

    Build infrastructure

  • Add support for W25Q80DV external flash chip. Thanks @lgnashold.
  • Allow CIRCUITPY drive name to be set in mpconfigboard.h. Thanks @mubes.
  • Fix a build alignment warning. Thanks @mubes.
  • Fix build checks for proper flash granularity for flash erases. Thanks @dhalbert.

New Boards

Find downloads for all boards, including these, at

New since 5.0.0-beta.5

  • SparkFun SAMD51 Thing Plus. Thanks @jepler.
  • Feather M7 1011. Thanks @arturo182.
  • Arduino Nano 33 IoT. Thanks @fgallaire.
  • PyCubed. Thanks @maholli.
  • Espruino Wifi. Thanks @hierophect.
  • Espruino Pico. Thanks @hierophect.
  • CircuitBrains Basic. Thanks @neubauek.
  • CircuitBrains Deluxe. Thanks @neubauek.

Breaking Changes and Deprecations from 4.x

  • 5.0.0 improves our internal filesystem definitions and may overwrite your existing files so make sure to back them up before updating!
  • The bleio module has been renamed to _bleio to indicate that it is meant to be used only for writing BLE libraries, and that its API may change between CircuitPython minor versions. There are many incompatible changes in _bleio since 4.0.0. Please use the latest adafruit_ble library for end-user BLE programming.
  • The displayio refresh API has been revamped to be simpler. wait_for_frame and refresh_soon have been removed. In both 4.x and 5.x, auto refresh will automatically refresh the display so they can be removed. The new auto_refresh property and refresh() function can be used to control when the screen refreshes and at a specific rate.
  • Moved audioio.Mixer to audiomixer.Mixer, which is only available on M4s. Moved audioio.RawSample, and audioio.WaveFile to the new module audiocore. However, for backwards compatibility, they are still available in audioio. They will be removed from audioio in 6.0.0. Thanks @jepler.
  • Added I2C.writeto_then_readfrom(). Deprecate stop= arg which will be removed in 6.x. Use I2C.writeto_then_readfrom() instead.
  • Removed re from CircuitPlayground Express Display build.
  • Removed gamepad from CircuitPlayground Express Crickit build.

Known Issues

  • displayio operations that read from an SD card (e.g., OnDiskBitmap) will interfere with other SD card operations and can cause lockup. To work around this problem, do not read or write files on the SD while the display is updating, and vice versa.
  • See for other issues.@


Thank you to all who used, tested, contributed, helped out, and participated on GitHub and/or Discord, including @arturo182, @bmeisels, @DavePutz, @dhalbert, @fgallaire, @hierophect, @jamesbowman, @jepler, @ladyada, @lgnashold, @maholli, @makermelissa, @mubes, @neubauek, @pdp7, @rhooper, @tannewt, @ATMakersBill, @AndrewTribble, @Anne B, @Antonio, @CGrover, @CarlFK, @Curt Olson, @Dar, @DaveP, @DavidGlaude, @DudeImOnly6, @Duewester, @KingerNorth, @SouthernDragon, @TG-Techie, @ThomasAtBBTF, @adafruit, @anecdata, @brentru, @cater, @charlesburnaford, @codeNSolder, @deshipu, @dherrada, @diegoMini+, @ednl, @foamyguy, @geekguy, @graham, @hexthat, @jasonp, @jerryn, @kattni, @kjw, @madbodger, @marius_450, @mscosti, @ntoll, @siddacious, @sommersoft, @stargirl, @timvictor, @v923z and surely more we have missed. Join us on the Discord chat to collaborate.


Documentation is available in

Here are all the changes since 5.0.0-beta.5.

This release is based on MicroPython 1.9.4 @25ae98f. Support upstream MicroPython by purchasing a PyBoard (from Adafruit here).


Check out this guide for info on common problems with CircuitPython. If you are still having issues, then post to the Adafruit Support Forums and join Discord.

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