STM32CubeF7/Projects/STM32F7308-DISCO/Examples/GPIO/GPIO_IOToggle/readme.txt

/**
/**
  @page GPIO_IOToggle GPIO IO Toggle example
  
  @verbatim
  ******************************************************************************
  * @file    GPIO/GPIO_IOToggle/readme.txt 
  * @author  MCD Application Team
  * @brief   Description of the GPIO IO Toggle 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 configure and use GPIOs through the HAL API. 

PA7 IO (configured in output pushpull mode) toggles in a forever loop.
On STM32F7308-DISCO board this IO is connected to LED5.

  This example provide different configuration for linker files which allows different eXecution in Place (XiP) schemas
  Supported configuration by STM32F7308-Discovery:
    - XiP From QSPI, DATA on Internal SRAM
    - XiP From QSPI, DATA on External PSRAM
  Make sure that chosen config matches ExtMem_Boot config in memory.h file.

@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 example needs to ensure that the SysTick time base is always set to 1 millisecond
      to have correct HAL operation.

@note The STM32F7xx devices can reach a maximum clock frequency of 216MHz but as this application uses SDRAM,
      the system clock is limited to 200MHz. Indeed proper functioning of the SDRAM is only guaranteed
      at a maximum system clock frequency of 200MHz.

@par Keywords

System, GPIO, Output, Alternate function, Push-pull, Toggle

@Note<74>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

 - "GPIO_IOToggle/Inc": contains the GPIO_IOToggle firmware header files
    - GPIO/GPIO_IOToggle/Inc/main.h                   Main configuration file
    - GPIO/GPIO_IOToggle/Inc/stm32f7xx_it.h           Interrupt handlers header file
    - GPIO/GPIO_IOToggle/Inc/stm32f7xx_hal_conf.h     HAL Configuration file

 - "GPIO_IOToggle/Src": contains the GPIO_IOToggle firmware source files
    - GPIO/GPIO_IOToggle/Src/main.c                   Main program
    - GPIO/GPIO_IOToggle/Src/stm32f7xx_hal_msp.c      Microcontroller specific packages initialization file.
    - GPIO/GPIO_IOToggle/Src/stm32f7xx_it.c           Interrupt handlers
    - GPIO/GPIO_IOToggle/Src/system_stm32f7xx.c       STM32F7xx system clock configuration file


@par Hardware and Software environment

  - This example runs on STM32F730xx devices.

  - This example has been tested with STMicroelectronics STM32F7308-DISCO
    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 (GPIO_IOToggle).
  4. Program the external QSPI memory with this example (see below).
  5. Start debugging this example 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 the 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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