CircuitPython 6.1.0-rc.1 released! @adafruit @circuitpython

CircuitPython 6.1.0-rc.1 is the second release candidate of CircuitPython 6.1.0. See Port status below for details on port stability, and Known Issues for known problems. If you find any issues with this release, please file an issue. If no significant issues are found within a few days, we’ll release this version as stable.

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).

Port status

CircuitPython has a number of “ports” that are the core implementation for a variety of microcontroller families. Stability varies on a per-port basis. As of this release, atmel-samd, nrf, and stm for the F4 family are stable. cxd56, esp32s2, and stm for other chip families are being actively improved but may be missing functionality and have bugs. litex and mimxrt10xx are in an alpha state and will have bugs and missing functionality.

Changes since 6.1.0 Release Candidate 0

Fixes and enhancements

  • Update ulab to version 1.6.1. #3972. Thanks @jepler.
  • Use double-quotes in initial program. #3973. Thanks @kattni.
  • Add len(alarm.sleep_memory) and bool(alarm.sleep_memory). #3958. Thanks @dhalbert.
  • Add native support for msgpack. #3659. Thanks @iot49.

Board- and port-specific changes

  • atmel-samd and nrf: Tick counter was being truncated when copied. #3939. Thanks @dhalbert.
  • atmel-samd:
    • Use correct TCC resolution for PWMOut. #3960. Thanks @dhalbert.
    • Use correct channel for AnalogOut. #3966. Thanks @dhalbert.
  • nrf:
    • Fix BLE timeout check for start_scan(). Round float BLE timing values instead of truncating. #3942, #2930. Thanks @dhalbert.
    • Don’t check length on gattc write for remote characteristics or descriptors. #3993. Thanks @dhalbert.
  • MagTag:
    • add accelerometer interrupt pin. #3940. Thanks @caternuson.
    • Add board.A1 as (preferred) name for `board.AD1. #4001. Thanks @dhalbert.
  • ESP32-S2:
    • Implement I2SAudioOut. #3733. Thanks @jepler.
    • Convert README to .rst. #3945. Thanks @2bndy5.
    • Correct data length for socket.recvfrom_into(). #3955. Thanks @caiokat.
    • Add sys.platform. #3954. Thanks @anecdata.
    • FeatherS2: Use DotStar for status LED. #3930. Thanks @jerryneedell.
    • Add network.authmode. #3944. Thanks @BennyE.
    • Add debug logging for all WiFi events; remove unneeded WiFi setup call. #3903. Thanks @anecdata.
    • Reduce power consumption when TouchAlarm not in use; allow multiple TouchAlarm pins. #3969. Thanks @microDev1.
  • TG-Watch: Multiple revisions, including frozen modules. #3991. Thanks @TG-Techie.

Build and infrastructure changes

  • Pass DEBUG make flag into code with CIRCUITPY_DEBUG preprocessor macro. #3957. Thanks @dhalbert.
  • Shrink some German builds that no longer fit. #3983. Thanks @dhalbert.
  • ESP32-S2: Fix make flash. #3982. Thanks @jepler.
  • Add robots.txt so search engines won’t crawl obsolete documentation in ReadTheDocs. #3291. Thanks @dhalbert.
  • Bump key for GitHub Actions cache to avoid bad cached data. #3997. Thanks @dhalbert.
  • Update uzlib to version 2.9.5, used in unix build. #4002. Thanks @jepler.
  • Fix parallel build problem for unix build. #4004. Thanks @jepler.


  • Translation additions and improvements. Thanks:
    • @wtuemura (Brazilian Portugese)
    • @HugoDahl (French)
    • @BumblebeeMan (German)

New boards since 6.1.0 Release Candidate 0

  • Adafruit Feather ESP32-S2 mini module with and without TFT display. #3959. Thanks @ladyada.
  • Adafruit NeoPixel Trinkey. #3978. Thanks @ladyada.

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.
  • The default speed of busio.I2C and board.I2C is now 100khz, not 400khz as before. Use busio.I2C to set the speed explicitly. #3471 Thanks @caternuson, @ladyada, @hierophect and @tannewt
  • _bleio.ConnectionError has be removed. Code will now raise the native ConnectionError instead.

Known issues

  • ESP32-S2: Crash when repeatedly creating and destroying busio.I2C object on ESP32-S2. #3846.
  • Built-in adafruit_bus_device has been disabled due to issues (#3859, #3856), please install the version from the Library Bundle
  • Writing several larger files to CIRCUITPY when there is no serial connection to the board can take a long time or hang. To speed up copying, open a serial (REPL) connection. #3986.
  • See for other issues.


Thank you to all who used, tested, and contributed since 6.1.0 Release Candidate 0, including @2bndy5, @anecdata, @BennyE, @BumblebeeMan, @caiokat, @caternuson, @dhalbert, @hugodahl, @jepler, @jerryneedell, @kattni, @ladyada, @microDev1, @sommersoft, @tannewt, @TG-Techie, @weblate, @wtuemura, and many others 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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