[PATCH rtems-docs] user/bsps: Add STM32H7 SDMMC driver
christian.mauderer at embedded-brains.de
Thu Mar 25 08:35:58 UTC 2021
user/bsps/arm/stm32h7.rst | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/user/bsps/arm/stm32h7.rst b/user/bsps/arm/stm32h7.rst
index 3eee511..483d029 100644
@@ -31,3 +31,29 @@ USB Host Driver
The USB host driver ``dwc_otg`` is provided by the ``libbsd``.
+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.
+* 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.
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