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CircuitPython 5.4.0 Beta 1 released!
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CircuitPython 5.4.0 Beta 1 released!

by tannewt on Tue Jun 09, 2020 4:55 pm

From the GitHub release page:
This is the second beta release of CircuitPython 5.4.0. This release adds basic lower power support when in time.sleep(). The lower power work changed time keeping and may have introduced bugs. Please use 5.3.0 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 5.4.0 Beta 0
  • New port for the ESP32-S2. Thanks to @tannewt, @jerryneedell, @jepler
  • New countio module to count pulses. Thanks to @LearnWeaver
  • New watchdog module to control built in WatchDog. Only on nRF52840 currently. Thanks to @xobs
  • New vectorio module for native displayio shapes. Thanks to @WarriorOfWire
  • New pre-commit hooks. Thanks to @flameeyes
  • Native module docs are now Python stubs. Thanks to @dherrada, @sommersoft and @tannewt
  • Add one directional UART support to iMX RT. Thanks to @hierophect
  • Add negative step support to PixelBuf. Thanks to @dunkmann00
  • Add support for anonymous BLE advertising. Thanks to @xobs
  • Add support for REPL over debug UART. Only on STM32. Thanks to @k0d
  • Add bytearray.decode() for improved CPython compatibility. Thanks to @theacodes
  • Fix garbled audio playback when voice 0 is stopped. Thanks to @jepler
  • Fix timekeeping on Spresence. Thanks to @kamtom480
  • Fix exception when no bus is found to match other ports (and be compatible with find pin combo scripts.) Thanks to @arturo182
  • Fix pulseio deinit issue on SAMD. Thanks to @daveputz
  • Fix USB race condition on SAMD. Thanks to @hathach
  • Fix microcontroller.cpu.temperature crash on iMX RT. Thanks to @arturo182
  • Fix gamepad and gamepadshift after lower power changes. Thanks to @jepler
  • Increase max SPI speed on iMX RT. Thanks to @arturo182
  • Allow setting RGBW pixels with RGB value. Thanks to @rhooper
  • Update ulab. Thanks to @jepler and @v923z
  • Clock configuration improvements on STM and iMX RT. Thanks to @hierophect
  • Add support for GD25S512MD flash chip. Thanks to @bd34n
  • New translations for Czech (cs) and Dutch (nl). Thanks to @dustinwatts, @vooralfred, @dronecz and @jepler.
  • Improved German, French and Swedish translations. Thanks to @bergdahl, @aberwag, @dglaude, Thomas Friehoff, @PTS93, and @jepler.
Full commit log is here.

New boards since 5.4.0 Beta 0
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 since 5.4.0 Beta 0, helped out, and participated on GitHub and/or Discord, including @aberwag, @arturo182, @bd34n, @bradchan, @DavePutz, @deshipu, @dglaude, @dhalbert, @dunkmann00, @flameeyes, @hathach, @hierophect, @jepler, @jerryneedell, @JoeBakalor, @jpecor, @kamtom480, @kattni, @k0d, @ladyada, @LearnWeaver, @maholli, @mew-cx, @nicell, @PTS93, @rhooper, @sommersoft, @spkuehl, @Teknikio, @theacodes, Thomas Friehoff, @v923z, @WarriorOfWire, @xiongyihui, @xobs and surely more we have missed. 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).

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 [b]Download from section above.[/b]

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Please be positive and constructive with your questions and comments.