.. _changelog_v3_6_0:

v3.6.0
======

v3.6.0 brings full **OV5640 5 MP** camera support with new high-resolution
framesizes (HD / FHD / QHD / QXGA / WQXGA), updates the core to **MicroPython
1.12**, heavily optimizes the software **JPEG encoder** and AprilTag / line
detection, adds **UVC (USB video) on the OpenMV Cam H7 Plus**, and supports
QSPI flash up to 32 MB. MicroPython behavior and ``get_histogram()`` changed —
read the breaking changes below.

.. contents:: On this page
   :local:
   :depth: 1

Highlights
----------

- **OV5640 5 MP** — full camera driver with new HD / FHD / QHD / QXGA /
  WQXGA / WQXGA2 framesizes.
- **MicroPython 1.12** — the bundled core was updated.
- **Faster pipeline** — heavily optimized software JPEG encoding, AprilTag
  detection, LSD line detection, ``histeq()``, and QR-code decoding.
- **UVC on H7 Plus** — the OpenMV Cam H7 Plus can act as a USB video device.
- **Breaking:** MicroPython behavior, ``image.get_histogram()`` normalization,
  and the OpenMV 3 JPEG/grayscale output changed — see the breaking changes.

New features
------------

- **OV5640** — added full support for the OV5640 5 MP camera (external clock
  configuration in sensor init) and the new ``sensor.HD`` / ``FHD`` / ``QHD``
  / ``QXGA`` / ``WQXGA`` / ``WQXGA2`` framesize constants.
- **TIM4** — freed up so it is usable from MicroPython.
- Added a DAC timed-write example (``dac_write_timed.py``) and renamed
  ``dac_control.py`` to ``dac_write.py``.

Other changes and improvements
------------------------------

- Updated the bundled MicroPython to 1.12; heavily optimized the software
  JPEG encoder (VGA path, grayscale/binary paths, integer instead of
  floating-point math, optimized MCU capture), LSD ``find_line_segments()``,
  AprilTag detection, ``Image.histeq()``, and QR-code / RGB-to-gray
  conversion; added QSPI flash support for chips up to 32 MB; removed the
  obsolete CMSIS-CNN ``cnn.py`` example.

Bug fixes
---------

Camera and imaging:

- Fixed JPEG encoding corruption at HQQQVGA, binary (1-bit) image → JPEG
  compression, a ``find_line_segments()`` regression (re-enabled the
  ``NOTDEF`` non-aligned check), and minor OV2640 driver issues.

System and boot:

- Fixed self-test / filesystem corruption (``selftest.py`` now runs before USB
  MSC is enabled, and USB MSC is enabled on a fatal error so the host can read
  the error log), the :class:`pyb.DAC` ``write_timed()``, the H7 :class:`machine.I2C`
  timings, F7 overdrive re-enable after stop mode, and the ``stop_mode.py``
  ``rtc.wakeup()`` interval.

Hardware and board support
--------------------------

- **OV5640** — full 5 MP camera driver with high-resolution framesizes.
- **OpenMV Cam H7 Plus** — UVC (USB video) support; the ``OPENMV4R`` board
  target was renamed ``OPENMV4P``.
- **QSPI flash** — chips up to 32 MB are now supported.

Breaking API changes
--------------------

User-visible API breaks between v3.5.2 and v3.6.0. Scope: Python C-modules in
``modules/`` and Python libraries in ``scripts/libraries/``.

All three breaking changes are *behavior* changes (same API, different
results) — re-check affected scripts. Each commit hash links to its diff on
GitHub.

.. _v3_6_0_micropython:

MicroPython updated to 1.12 *(behavior)*
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The bundled MicroPython core was updated to 1.12. Standard-library and
language behavior follows upstream MicroPython 1.12; re-check scripts that
depend on version-specific :mod:`micropython` / standard-module behavior.

*Commits:* `eafd431ea <https://github.com/openmv/openmv/commit/eafd431ea>`__

.. _v3_6_0_histogram:

``image.get_histogram()`` threshold normalization changed *(behavior)*
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``image.get_histogram()`` (and ``get_statistics()``) with color thresholds now
normalizes by the number of thresholded pixels rather than the whole ROI, and
uses floor instead of round for bin indexing. Histogram/statistics values for
thresholded calls differ from previous releases — re-tune code that compared
against absolute histogram values.

*Commits:* `7cf0f8089 <https://github.com/openmv/openmv/commit/7cf0f8089>`__

.. _v3_6_0_omv3yuv:

OpenMV 3 JPEG/grayscale output changed *(behavior)*
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To save flash, the OpenMV 3 (M7) YUV lookup table was disabled, so JPEG and
grayscale output pixel values are computed slightly differently on the
OpenMV 3. Output is still valid but differs marginally from prior releases;
re-check pixel-exact comparisons on the OpenMV 3.

*Commits:* `0e4b46e41 <https://github.com/openmv/openmv/commit/0e4b46e41>`__

.. _v3_6_0_migration:

Migration checklist
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Re-validate scripts that depend on version-specific MicroPython behavior
against 1.12 (:ref:`the MicroPython bump <v3_6_0_micropython>`), re-tune code
that compared against absolute ``get_histogram()`` / ``get_statistics()``
values when using color thresholds
(:ref:`the histogram change <v3_6_0_histogram>`), and re-check pixel-exact
comparisons on the OpenMV 3 (:ref:`the OpenMV 3 output change
<v3_6_0_omv3yuv>`). All other scripts run unchanged.