.. SPDX-License-Identifier: CC-BY-SA-4.0

.. Copyright (C) 2020 embedded brains GmbH

stm32h7
=======

This BSP supports the
`STM32H7 Series <https://www.st.com/en/microcontrollers-microprocessors/stm32h7-series.html>`_.

The BSP is known to run on these boards:

* `STM32H743I-EVAL 2 <https://www.st.com/en/evaluation-tools/stm32h743i-eval.html>`_
* `STM32H743ZI-Nucleo <https://www.st.com/en/evaluation-tools/nucleo-h743zi.html>`_

Clock Driver
------------

The clock driver uses the `ARMv7-M Systick` module. The HSE (external
oscillator) value can also be different for different evaluation or custom
boards, so it is recommended to check the default values of the BSP.

Console Driver
--------------

The console driver supports the on-chip UART and USART modules.
Different board variations use different GPIO pins and blocks for the default
communication UART and it is recommended to check whether the default
configuration provided is valid in the BSP.

To specify that the BSP should be built for the STM32H743ZI-Nucleo board,
users can supply ``STM32H743ZI_NUCLEO = True`` to ``config.ini`` when
building the BSP.

Alternatively, users can supply the configuration structs defined in ``hal.h``
in the application for other boards. For the console driver, the
``stm32h7_usartX_config`` structs are used to configure the GPIO pins and other
parameters. The default implementations can be found in
``bsps/arm/stm32ht/console`` in the RTEMS sources.

Network Interface Driver
------------------------

The network interface driver ``if_stmac`` is provided by the ``libbsd``.

USB Host Driver
---------------

The USB host driver ``dwc_otg`` is provided by the ``libbsd``.

SD/MMC Driver
-------------

The SDMMC driver ``st_sdmmc`` is provided by the ``libbsd``.

The default initialization is done for the STM32H743I-EVAL 2 board.

To use different pins, you can create a ``HAL_SD_MspInit()`` function in your
application that overwrites the default one defined in ``RTEMS``. If you don't
have direction lines like on the evaluation board, you can just skip
initializing these pins.

If you want to use a different number of data lines, another polarity for the
data direction pins, a different voltage or similar, you have to redefine
``st_sdmmc_get_config()`` (normally provided by ``libbsd``) in your application.

Known limitations:

* Currently 1.8V signaling is not implemented. Therefore higher speeds like used
  for UHS cards are not available. All cards fall back to High Speed transfers.
* The driver uses the IDMA only. MDMA is currently not implemented. For SDMMC1
  that means that the memory buffers can only come from AXI SRAM, QSPI memory,
  Flash or the FMC (SDRAM, ...). The internal SRAM1, SRAM2, SRAM3 and SRAM4 is
  not supported. SDMMC2 should not have that limitation. See ST AN5200 "Getting
  started with STM32H7 Series SDMMC host controller" for more details.