CircuitPython 4.0.0 Beta 1 released!

From the GitHub release page:

This release includes a number of bug fixes to bleio and displayio since Beta 0.

This is a beta build of 4.0.0. There are still issues to fix before stable and the new APIs may evolve a bit more. Please use the latest 3.x stable release when first starting with CircuitPython. It is stable.

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

4.0.0

4.0.0 is the latest major revision of CircuitPython and features support for the nRF52840 BLE chipset and translated messages.

Installation

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).

Most builds are available as both UF2 and bin files here along with test builds.

New Features, Updates, and Fixes since Beta 0

• bleio fixes that make it work with newer iOS devices and Android. Thanks to @dhalbert
• Fix bleio docs. Thanks to @dhalbert
• Fix time.struct_time() incorrect argument checking. Thanks to @jerryneedell
• Fix color computation in displayio.Palette and make init code more USB friendly. Thanks to @tannewt
• Translation updates:
  • German thanks to @Tasm-Devil

New Boards

• SparkFun SAMD21 Dev. Thanks to @ShawnHymel

Breaking Changes from 3.x!

• busio.UART breaking changes to match PySerial. Thanks to @dhalbert
  • busio.UART constructor timeout parameter is now in seconds instead of milliseconds
  • UART.readinto(buf) now does not allow an optional length parameter UART.readinto(buf, len)
  • UART.write(…) no longer allows strings to be written. The bytes written must be bytes or bytearray or an array.array.
• framebuf has been removed. displayio is its replacement, and will be enhanced after 4.0 to include framebuf‘s functionality.
• Improve struct compatibility with CPython by enforcing stricter types. This may break your code! Thanks to @dhalbert

Known Issues

Thanks

Thank you to all who used, tested, contributed, helped out, and participated on GitHub and/or Discord:
@ladyada, @dhalbert, @tannewt, @kattni, @microbuilder, @hathach, @arturo182, @nickzoic, @glennrub, @siddacious, @deshipu, @sommersoft, @jerryneedell, @brentru, @caternuson, @jepler, @urish, @sajattack, @notro, @Jahor, @Makdaam, @mrmcwethy, @jepler, @notro, @mattyt, @furlaneto, @ATMakersBill, @Klowner, @klardotsh, @C47D, @carlosperate, @platipo, @xpecex, @gcvasconcelos, @saspa, @uhrheber, @nickzoic, @sabas1080, @sajattack, @JoshuaLowe1002, @Senuros, @mchobby, @Retoc, @CedarGroveStudios, @bwshockley, @yeyeto2788, @jimblom, @rhooper, @ShawnHymel, @TG-Techie, @eighthree, @arofarn, @chalei, @vgoodwinv, @gpshead, @dsiee, @Tasm-Devil, @larsks, @CarlFK and surely more we have missed. Join us on the Discord chat to collaborate.

Documentation

Documentation is available in readthedocs.io.

Here are all the changes since 4.0.0-beta.0.
Here are all the changes since 3.1.2.

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

Troubleshooting

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