CircuitPython 9.1.0 Beta 3 Released!

From the GitHub release page:

This is CircuitPython 9.1.0-beta.3, a beta for CircuitPython 9.1.0, and is a new unstable release. This release has known bugs that will be addressed before 9.1.0 final.

WARNING for nRF52 boards only: If your board has an nRF52 UF2 bootloader whose version is before 0.6.1, you will not be able to load CircuitPython 8.2.0 and later, due to increased size of the firmware. See these instructions for updating your bootloader.

Notable changes since 9.0.0

Incompatibility warnings

  • API changes to floppyio.
  • String values in settings.toml must be quoted.


  • RP2040 I2SOut supports BLCK and LRCLK in either order.
  • ESP32-S3 supports audiomp3.


  • Initial implementation of BLE GATT server support on Espressif chips. Pairing/bonding is not yet implemented.

Built-in modules

  • Enhance collections.deque functionality.
  • Add keypad_demux.DemuxKeyMatrix: use multiplexer for one side of a keypad matrix.
  • Add integration-based debouncing to keypad.
  • supervisor.Runtime.serial_bytes_available now returns a count instead of a bool.
  • Incompatible change: floppyio improvements, including API changes.


  • fourwire.FourWire: chip_select pin is now optional.
  • picodvi now supports 640×240 and 800×240 resolutions.


  • Espressif: update to ESP-IDF v5.2.1.
  • Espressif: Change task-switching quantum to 1 millisecond from 10 milliseconds.


  • Implement ssl module for anything that provides socket.


  • New port for renode hardware simulator.


  • String values in settings.toml must be quoted.


  • max3421e USB host support.
  • Allow user-specified names for usb_midi interfaces and jacks.

Download from

Firmware downloads are available from the downloads page on The site makes it easy to select the correct file and language for your board.


To install follow the instructions in the 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).


Documentation is available in

Port status

CircuitPython has a number of “ports” that are the core implementations for different microcontroller families. Stability varies on a per-port basis. As of this release, these ports are consider stable (but see Known Issues below):

  • atmel-samd: Microchip SAMD21, SAMx5x
  • cxd56: Sony Spresense
  • espressif: Espressif ESP32, ESP32-S2, ESP32-S3, ESP32-C2, ESP32-C3, ESP32-C6
  • nordic: Nordic nRF52840, nRF52833
  • raspberrypi: Raspberry Pi RP2040
  • stm: ST STM32F4 chip family

These ports are considered alpha and will have bugs and missing functionality:

  • broadcom: Raspberry Pi boards such as RPi 4, RPi Zero 2W
  • litex: fomu
  • mimxrt10xx: NXP i.MX RT10xxx
  • renode: hardware simulator
  • silabs: Silicon Labs MG24 family
  • stm: ST non-STM32F4 chip families

Changes since 9.1.0-beta.2

Fixes and enhancements

  • Update frozen libraries. In particular, fixes an issue introduced in 9.1.0-beta.2 with the adafruit_esp32spi library. #9271. Thanks @dhalbert.
  • Fix exception chaining for non-built-in exceptions #9269, #9266. Thanks @jepler.
  • Update TinyUSB; includes USB host fixes. #9252. Thanks @todbot.
  • Calculate synthio.LFO.value at construction. #9247. Thanks @jepler.

Port and board-specific changes



  • Initial implementation of BLE GATT server support on Espressif chips. Pairing/bonding is not yet implemented. #9222. Thanks @tannewt.





  • Pico W: set socket connected status after UDP and raw connect. #9251. Thanks @jepler.





Individual boards

  • Espressif ESP2-S3-DevKitM-1: add GPIO34 pin. #9259. Thanks @fetsnleds.
  • M5Stack CoreS3: enable on-board camera and microphone. #9255. Thanks @CDarius.

Documentation changes

Build and infrastructure changes

  • Use raw strings for Python regular expressions. #9267. Thanks @dhalbert.
  • Replace all uses of STATIC with static in CircuitPython-only C source files. #9263. Thanks @dhalbert.
  • Replace include guards with #pragma once in CircuitPython-only C header files. #9262, #9260. Thanks @dhalbert.
  • Mark all CircuitPython-only C sources files as being part of the CircuitPython project. Change to use SPDX for copyright lines and licenses for these files. Remove in-line MIT license text. Add headers to files that did not have them. #9257. Thanks @dhalbert.

Translation additions and improvements

New boards since 9.1.0-beta.2

  • Bradán Lane STUDIO Explorer Badge. #9256. Thanks @bradanlane.
  • Freenove ESP32-WROVER-DEV-CAM (and other similar generic boards). #9233. Thanks @gitcnd.

Known issues

  • See for other issues, including issues still to be addressed for:


Thank you to all who used, tested, and contributed since 9.1.0-beta.2, including the contributors above, and many others on GitHub and Discord. Join us on the Discord chat to collaborate.

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