CircuitPython 6.0.0-alpha.3 released! @adafruit @circuitpython

This is the third alpha release of CircuitPython 6.0.0. It is relatively stable. The release is still alpha because some API changes and additions are not yet included. Upcoming in a future release but not yet included are ESP32-S2 Wifi support, and _bleio HCI support for ESP32 co-processors.

The most notable additions since 5.3.x are basic lower power support when in time.sleep() and initial ESP32-S2 support. The lower power work changed time keeping and may have introduced bugs. Please use 5.3.x if you need a stable version of CircuitPython.

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. Downloads are no longer available from the GitHub release pages because of the large number of files for each release.


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 and improvements since 6.0.0 Alpha 2

API changes

  • Disable socket, wiznet5k and network modules. They will be removed in 7.x in favor of networking libraries. Thanks @tannewt.
  • Add memorymonitor for memory debugging. It must be enabled on a local build. Thanks @tannewt.
  • Add .find, .rfind, .index and .rindex to bytearray for CPython-compatible builds. Thanks @tannewt.
  • json.load now works with any object with readinto. Thanks @tannewt.
  • pulseio.PWMOUT is split out into pwmio.PWMOut. It is still available in pulseio, but that is deprecated and will be removed in 7.x (#3299). Thanks @tannewt.
  • _bleio: Allow changing MAC address (#3276). Thanks @xiongyihui.
  • _pixelbuf now supports iterables and floats (#3260). Thanks @rhooper.
  • nrf: Turn off QSPI when sleeping (#3244). Thanks @xiongyihui.
  • Add coroutine behavior for generators (#3178). Thanks @WarriorOfWire.


  • UTF-8 handled properly in REPL (#3305, #3243). Thanks @dunkmann00.
  • terminalio is disabled for Japanese and Korean translations, because we currently have no font available (#3295). Thanks @tannewt.
  • Fix storage management in displayio (#3292). Thanks @jepler.
  • nrf: Code error in _bleio (#3284). Thanks @kevinjwalters for finding it, and @dhalbert for the fix.
  • nrf: SPIM3 buffer was in the wrong place. Thanks @riggs for pointing out the error, and @dhalbert for the fix.
  • ESP32-S2: Fix writing sector 0 in filesystem (#3262). Thanks @tannewt.
  • sharpdisplay: Prevent pin in use error (#3277). Thanks @jepler.
  • Improve high-speed USB (#3225). Thanks @hathach.
  • Allow assigment to 32-bit Bitmap (#3227). Thanks @cwalther.
  • Prevent crashing Linux when doing storage.erase_filesystem() (#3323). Thanks @dhalbert.
  • async for __aiter__ fix (#3222). Thanks @WarriorOfWire.
  • Improve appearance of vectorio.Polygon (#3221). Thanks @WarriorOfWire.
  • Fix displayio.Group.insert(). (#3214). Thanks @kmatch98.
  • Allow larger pystack on SAMD21 (#3213). Thanks @jerryneedell.
  • await must be inside an async def (#3202). Thanks @WarriorOfWire.

Board- and port-specific changes

  • ESP32-S2: enable ulab (#3325), add neopixel_write (#3280, #3232), PulseOut, PulseIn (#3279), enabled random (#3324). Thanks @hierophect.
  • STM: fix random (#3324). Thanks @hierophect.
  • ESP32-S2: add PSRAM support (#3315). Thanks @tannewt.
  • Mini Sam M4 additional flash chip (#3308). Thanks @bwshockley.
  • Spresense: USB updates (#3306). Thanks @kamtom48.
  • SAME54: use correct macro constants (#3303). Thanks @jepler.
  • Simmel: update to reflect actual hardware (#3297). Thanks @bunnie.
  • RFM9x M0: freeze in RFM library (#3251). Thanks @jerryneedell.
  • Update frozen libraries for all boards (#3240). Thanks @jerryneedell.
  • Open Book: updates (#3226). Thanks @joeycastillo.
  • Wio Terminal: add displayio.DISPLAY (#3215). Thanks @ansonhe97.
  • Fluff M0: add pin aliases (#3209). Thanks @deshpu.
  • Commander: add GamePad (#3020) . Thanks @burtyb.
  • Litex: improve pin handling (#3199). Thanks @hierophect.


  • Numerous translation additions and improvements. Thanks:
    • @wtuemura (Brazilian Portugese)
    • @hexthat (Pinyin)
    • @ciscorn (Japanese)
    • @fede2cr, @dherrada (Spanish)
    • @bergdahl (Swedish)
    • @ryevertigo (Dutch)
    • @NathanBnm (French)
  • Translation detail and infrastructure fixes (#3283, #3282, #3241). Thanks @jepler.
  • Build PDF documentation on readthedocs (#3286). Thanks @sommersoft.
  • Add links to boards in the Support Matrix (#3256). Thanks @sommersoft.
  • Fix readthedocs build errors (#3255). Thanks @ciscorn.
  • Improve core modules documentation (#3252). Thanks @ciscorn.
  • Set version and release for sphinx (#3246). Thanks @sommersoft.
  • Add many type hints in documentation (#3193). Thanks @ciscorn.
  • Fix order of doc build to fix readthedocs (#3335). Thanks @jepler.
  • Fix and speed up support matrix generation (#3331). Thanks @jepler.

Internals and build process

  • Check for too many USB endpoints needed (#3304). Thanks @jepler.
  • Compress messages more efficiently by not including QSTR’s (#3298). Thanks @ciscorn.
  • Squeeze builds to fit new translations (#3273, #3236, #3230). #3236 in particular saved a lot of space in a math routine. Thanks @jepler.
  • Report number of missing displayio font characters for messages (#3300). Thanks @jepler.
  • Less verbose build logs (#3290). Thanks @jepler.
  • Fix mpy-cross dependency analysis during make (#3239). Thanks @jepler.
  • Fix gcc10 compilation issues (#3231, #3218). Thanks @jepler and @tannewt.
  • Upload mpy-cross builds to Amazon S3 (#3220). Thanks @dhalbert.
  • Fix compilation on Windows msys (#3219). Thanks @ladyada.
  • Fix doc-building dependencies (#3212). Thanks @tannewt.
  • Parallelize GitHub CI builds (#3203). Thanks @WarriorOfWire.
  • Allow different compiler optimizations per board. Choose faster optimization on boards that have the space (#3190). Thanks @DavePutz.
  • Fix same-line comment issue in makefiles (#3333). Thanks @hierophect.

Full commit log is here.

Breaking changes since 5.x

  • i2cslave is now i2cperipheral and the class in it is changed as well.
  • The stop kwarg has been removed from I2C.writeto(). If no stop is desired, then use writeto_then_readfrom.

New boards since 6.0.0 Alpha 2

  • Picoplanet (#3267). Thanks @bleeptrack.
  • BLM Badge (#3217). Thanks @dhalbert.
  • Ikigaisense Vita nRF52840 (#3196). Thanks @IkigaiSense.
  • microDev microS2 (ESP32-S2) (#3302). Thanks @microDev1, and thanks to @jepler for fixing a line-ending issue (#3330).
  • Bastwifi by Electronic Cats (#3238). Thanks @sabas1080.

Known issues

  • Use of the adafruit_sdcard library can interfere with displayio operations that use read from an SD card (e.g., OnDiskBitmap). Use the native sdcardio or sdio modules instead, to avoid this problem.
  • See for other issues.


Thank you to all who used, tested, and contributed since 6.0.0 Alpha 2, including @anecdata, @ansonhe97, @bergdahl, @bleeptrack, @brentru, @bunnie, @burtyb, @bwshockley, @ciscorn, @cwalther, @DavePutz, @deshipu, @dhalbert, @dpgeorge, @dunkmann00, @fede2cr, @FoamyGuy, @hathach, @hexthat, @hierophect, @jepler, @jerryneedell, @joeycastillo, @jonathanhogg, @josecastillo, @kamtom480, @kmatch98, @ladyada, @microDev1, @rhooper, @ryevertigo, @sabas1080, @sommersoft, @tannewt, @WarriorOfWire, @weblate, @wtuemura, @xiongyihui, and many more on Discord. Join us on the Discord chat to collaborate.


Documentation is available in

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


One important feature of CircuitPython is translated control and error messages. With the help of fellow open source project Weblate, we’re making it even easier to add or improve translations. Sign in with an existing account such as Github, Google or Facebook and start contributing through a simple web interface. No forks or pull requests needed!


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.


Builds are no longer stored as assets on this release page, because there are too many of them. Please see the Download from section above.

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