v4.2.2#

v4.2.2 adds PNG image support (decode/encode via lodepng), a table-driven built-in-model loader, Portenta OV5640 support, an Edge-Impulse TensorFlow update, and ulab 4.0. The RPC CAN configuration API changed — read the breaking changes below.

Highlights#

  • PNG support — Image.to_png(), image.PNG, and PNG file read/write.

  • tf.load_builtin_model() — table-driven built-in models that can be replaced or added at build time.

  • Portenta H7 — OV5640 camera support (with autofocus).

  • MicroPython/ulab — ulab updated to 4.0.0.

  • Breaking: the RPC CAN configuration API changed — see the breaking changes.

New features#

  • PNG image format — a new Image.to_png() method, an image.PNG / PIXFORMAT_PNG constant, PNG file load/save (read/write .png), and PNG output in image.to() conversions, via the integrated lodepng codec.

  • tf.load_builtin_model(path) — loads a firmware-built-in model and returns a (labels, net) tuple; built-in models are now table-driven so they can be replaced or added at build time.

Other changes and improvements#

  • TensorFlow / Edge Impulse — the bundled inference library was updated to Edge Impulse ei-V2.5.0, the person_detection model moved into the built-in model table, and missing TensorFlow operators were added across all Cortex-M0+/M4/M7/M55 builds so more Edge Impulse models run.

  • ulab updated to 4.0.0.

  • Opening the USB virtual serial port at 1200 bps now triggers an Arduino-style touch reset into the bootloader.

  • The WINC1500 WiFi module firmware was updated to 19.7.6 (with the updater script), and it now reports the actual host-driver version.

  • The RP2 port prints “MPY: soft reboot” and gained UART init/de-init.

Bug fixes#

  • Fixed the Arduino Nano RP2040 Connect raw frame-buffer size and the Arduino Nicla Vision USB Product ID (correct USB enumeration).

Hardware and board support#

  • Arduino Portenta H7 — OV5640 camera support (with autofocus); the GC2145 is disabled on the Portenta.

  • Arduino Nano RP2040 Connect — memory configuration and fresh-filesystem templates.

  • WiFi Shield (WINC1500) — firmware updated to 19.7.6.

Breaking API changes#

User-visible API breaks between v4.2.1 and v4.2.2. Scope: Python C-modules in modules/ and Python libraries in scripts/libraries/.

Each change is tagged with its impact:

  • minor — narrow API; only affects scripts that used it.

  • behavior — same API, different results; re-check tuned scripts.

Changes are grouped by impact in that order. Each commit hash links to its diff on GitHub.

RPC CAN configuration API (minor)#

In the rpc library, the rpc_can_master / rpc_can_slave CAN keyword argument sampling_point was renamed to sample_point (to match upstream MicroPython), and the manual CAN bit-timing helper was removed — the CAN bus is now configured via CAN(..., baudrate=, sample_point=). Scripts that passed sampling_point or relied on the old bit-timing computation must be updated.

Commits: b565eca58, 06d716986

image.format() and compressed images (behavior)#

With the unified compressed-image path added for PNG, image.format() now returns PIXFORMAT_INVALID for an unknown format, and compressed-image indexing / iteration / printing now covers PNG as well as JPEG. Code that inspected the previous return value for unknown formats should be re-checked.

Commit: f12a4659c

Migration checklist#

For a clean port to v4.2.2: rename RPC CAN sampling_point → sample_point and drop any manual CAN bit-timing setup (the RPC CAN change), and re-check any code that inspected image.format() for unknown formats (the format() change).