This release contains new libraries and functionality, along with numerous bug fixes and documentation improvements.

Highlights are listed below, or you can see the full list of individual commits here, and the full list of resolved issues here.

Note, these release notes are long and may appear truncated in the “Releases” tab; you can see the full version here.

New Board Support

The following boards have been added and may be specified via PICO_BOARD:

• nullbits_bit_c_pro
• waveshare_rp2040_lcd_1.28
• waveshare_rp2040_one

Library Changes/Improvements

hardware_clocks

• clock_gpio_init() now takes a float for the clock divider value, rather than an int.
• Added clock_gpio_init_int_frac() function to allow initialization of integer and fractional part of the clock divider value, without using float.
• Added --ref-min option to vocalc.py to override the minimum reference frequency allowed.
• vocalc.py now additionally considers reference frequency dividers greater than 1.

hardware_divider

• Improved the performance of hw_divider_ functions.

hardware_dma

• Added dma_sniffer_set_output_invert_enabled() and dma_sniffer_set_output_reverse_enabled() functions to configure the DMA sniffer.
• Added dma_sniffer_set_data_accumulator() and dma_sniffer_get_data_accumulator() functions to access the DMA sniffer accumulator.

hardware_i2c

• Added i2c_get_instance() function for consistency with other hardware_ libraries.
• Added i2c_read_byte_raw(), i2c_write_byte_raw() functions to directly read and write the I2C data register for an I2C instance.

hardware_timer

• Added hardware_alarm_claim_unused() function to claim an unused hardware timer.

pico_cyw43_arch

• Added cyw43_arch_wifi_connect_bssid_ variants of cyw43_arch_wifi_connect_ functions to allow connection to a specific access point.
• Blocking cyw43_arch_wifi_connect_ functions now continue trying to connect rather than failing immediately if the network is not found.
• cyw43_arch_wifi_connect_ functions now return consistent return codes (PICO_OK, or PICO_ERROR_XXX).
• The pico_cyw43_arch library has been completely rewritten on top of the new pico_async_context library that generically abstracts the different types of asynchronous operation (poll, threadsafe_background and freertos) previously handled in a bespoke fashion by pico_cyw43_arch. Many edge case bugs have been fixed as a result of this. Note that this change should be entirely backwards compatible from the user point of view.
• cyw43_arch_init() and cyw43_arch_deinit() functions are now very thin layers which handle async_context life-cycles, along with adding support for the cyw43_driver, pico_lwip etc. to that async_context. Currently, these mechanisms remain the preferred documented way to initialize Pico W networking, however you are free to do similar initialization/de-initialization yourself.
• Added cyw43_arch_set_async_context() function to specify a custom async_context prior to calling cyw43_arch_init*()
• Added cyw43_arch_async_context() function to get the async_context used by the CYW43 architecture support.
• Added cyw43_arch_init_default_async_context() function to return the async_context that cyw43_arch_init*() would initialize if one has not been set by the user.
• Added cyw43_arch_wait_for_work_until() function to block until there is networking work to be done. This is most useful for poll style applications that have no other work to do and wish to sleep until cyw43_arch_poll() needs to be called again.

pico_cyw43_driver

• The functionality has been clarified into 3 separate libraries:
  • cyw43_driver – the raw cyw43_driver code.
  • cyw43_driver_picow – additional support for communication with the Wi-Fi chip over SPI on Pico W.
  • pico_cyw43_driver – integration of the cyw43_driver with the pico-sdk via async_context
• Added CYW43_WIFI_NVRAM_INCLUDE_FILE define to allow user to override the NVRAM file.

pico_divider

• Improved the performance of 64-bit divider functions.

pico_platform

• Add panic_compact() function that discards the message to save space in non-debug (NEBUG defined) builds.

pico_runtime

• Added proper implementation of certain missing newlib system APIs: _gettimeofday(), _times(), _isatty(), _getpid().
• The above changes enable certain additional C/C++ library functionality such as gettimeofday(), times() and std::chrono.
• Added settimeofday() implementation such that gettimeofday() can be meaningfully used.
• Added default (return -1) implementations of the remaining newlib system APIs: _open(), _close(), _lseek(), _fstat(), _isatty(