STM32CubeF7/Projects/STM32F7308-DISCO/Examples/DMA/DMA_FLASHToRAM/readme.txt

/**
  @page DMA_FLASHToRAM DMA FLASH To RAM Example

  @verbatim
  ******************************************************************************
  * @file    DMA/DMA_FLASHToRAM/readme.txt
  * @author  MCD Application Team
  * @brief   Description of the DMA FLASH to RAM example.
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2018 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  @endverbatim

@par Example Description

How to use a DMA to transfer a word data buffer from Flash memory to embedded
SRAM through the HAL API.

In this example, the code is executed from QSPI external memory while data are
in internal SRAM memory.

At the beginning of the main program the HAL_Init() function is called to reset
all the peripherals, initialize the Flash interface and the systick.
Then the SystemClock_Config() function is used to configure the system
clock (SYSCLK) to run at 216 MHz.

DMA2_Stream0 is configured to transfer the contents of a 32-word data
buffer stored in Flash memory to the reception buffer declared in RAM.

The start of transfer is triggered by software. DMA2_Stream0 memory-to-memory
transfer is enabled. Source and destination addresses incrementing is also enabled.
The transfer is started by setting the stream enable bit for DMA2_Stream0.
At the end of the transfer a Transfer Complete interrupt is generated since it
is enabled and the callback function (customized by user) is called.

STM32F7308-DISCO board's LEDs can be used to monitor the transfer status:
 - LED6 is ON when the transfer is complete (into the Transfer Complete interrupt
   routine).
 - LED6 is Toggled with a period of 200 ms when there is a transfer error
 - LED5 is ON when a Error_Handler is called

It is possible to select a different stream for the DMA transfer
example by modifying defines values in the file main.h.
Note that only DMA2 stream are able to perform Memory-to-Memory transfers.

@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
      based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from
      a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower)
      than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
      To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.

@note The application need to ensure that the SysTick time base is always set to 1 millisecond
      to have correct HAL operation.

@par Keywords

System, DMA, Data Transfer, Memory to memory, Stream, Flash, RAM

@Note If the user code size exceeds the DTCM-RAM size or starts from internal cacheable memories (SRAM1 and SRAM2),that is shared between several processors,
      then it is highly recommended to enable the CPU cache and maintain its coherence at application level.
      In case of constraints it is possible to configure the MPU as "Write through/not shareable" to guarantee the cache coherence at write access but the user
      has to ensure the cache maintenance at read access though.
      The address and the size of cacheable buffers (shared between CPU and other masters)  must be properly updated to be aligned to cache line size (32 bytes).

@Note It is recommended to enable the cache and maintain its coherence, but depending on the use case
      It is also possible to configure the MPU as "Write through", to guarantee the write access coherence.
      In that case, the MPU must be configured as Cacheable/Bufferable/Not Shareable.
      Even though the user must manage the cache coherence for read accesses.
      Please refer to the AN4838 “Managing memory protection unit (MPU) in STM32 MCUs”
      Please refer to the AN4839 “Level 1 cache on STM32F7 Series”

@par Directory contents

  - DMA/DMA_FLASHToRAM/Src/system_stm32f7xx.c    STM32F7xx system clock configuration file
  - DMA/DMA_FLASHToRAM/Src/stm32f7xx_it.c        Interrupt handlers
  - DMA/DMA_FLASHToRAM/Src/main.c                Main program
  - DMA/DMA_FLASHToRAM/Inc/stm32f7xx_hal_conf.h  HAL Configuration file
  - DMA/DMA_FLASHToRAM/Inc/stm32f7xx_it.h        Interrupt handlers header file
  - DMA/DMA_FLASHToRAM/Inc/main.h                Main program header file


@par Hardware and Software environment

  - This example runs on STM32F730xx devices.

  - This example has been tested with STMicroelectronics STM32F7308 Discovery
    boards and can be easily tailored to any other supported device
    and development board.


@par How to use it ?

In order to make the program work, you must do the following:

  1. Select required configuration in memory.h in Templates\ExtMem_Boot\Inc.
  2. Program the internal Flash with the ExtMem_Boot (see below).
  3. Use corresponding project configuration for this example.
  4. Program the external QSPI memory with this example (see below).
  5. Start debugging user application or reset for free running.

In order to load the ExtMem_Boot code :
   - Open your preferred toolchain :
      - Open the Project
      - Rebuild all files
      - Load project image

In order to load this example to the external memory:
   - Open your preferred toolchain
      - Open the Project
      - Use project matching ExtMem_Boot selected configuration
      - Rebuild all files:
      - Run & debug the program:
      - For an XiP configuration (eXecute in Place from QSPI):
          - Using EWARM or MDK-ARM : Load project image from the IDE: Project->Debug
          - Using SW4STM32 :
            - Open the STM32CubeProgrammer tool
            - Select the QSPI external flash loader "MX25L512G_STM32F7308-DISCO"
            - From Erasing & Programming menu, browse and open the output binary file relative to this example
            - Load the file into the external QSPI flash using "Start Programming" at the address APPLICATION_ADDRESS (0x90000000)


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