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).