STM32CubeF4

/**
  @page QSPI_PreInitConfig QSPI pre-init configuration example
  
  @verbatim
  ******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
  * @file    QSPI/QSPI_PreInitConfig/readme.txt 
  * @author  MCD Application Team
  * @brief   Description of the code execution from QSPI memory example.
  ******************************************************************************
  *
  * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *   1. Redistributions of source code must retain the above copyright notice,
  *      this list of conditions and the following disclaimer.
  *   2. Redistributions in binary form must reproduce the above copyright notice,
  *      this list of conditions and the following disclaimer in the documentation
  *      and/or other materials provided with the distribution.
  *   3. Neither the name of STMicroelectronics nor the names of its contributors
  *      may be used to endorse or promote products derived from this software
  *      without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  @endverbatim

@par Example Description

How to configure the QSPI IP in order to have access to external memory just after reset.

This example describes how to execute a part of the code from the QSPI memory. To do this, 
a section is created where the function is stored.

The QSPI is configured in memory-mapped mode before to call main() function and QSPI memory 
is then available after the reset. 

The configuration of the QSPI is done in the file system_stm32f4xx.c file in the 
function SystemInit_ExtMemCtl(). It is called by the function SystemInit(), which
is the first function called by the Reset_Handler.

The code in executed in a forever loop. It is the same code as GPIO_IOToggle example 
with some code mapped in QSPI mode and other in Flash, to show the jump from one 
memory to the other.

LED1, LED2, LED3 and LED4 toggle in this forever loop.

In this example, HCLK is configured at 100 MHz.

@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

Memory, QSPI, Erase, Write, DMA, section, memory-mapped mode, PreInit configuration, Jump

@par Directory contents 

  - QSPI/QSPI_PreInitConfig/Inc/stm32f4xx_hal_conf.h HAL configuration file
  - QSPI/QSPI_PreInitConfig/Inc/stm32f4xx_it.h       Interrupt handlers header file
  - QSPI/QSPI_PreInitConfig/Inc/main.h               Header for main.c module  
  - QSPI/QSPI_PreInitConfig/Src/stm32f4xx_it.c       Interrupt handlers
  - QSPI/QSPI_PreInitConfig/Src/main.c               Main program
  - QSPI/QSPI_PreInitConfig/Src/system_stm32f4xx.c   STM32F4xx system source file
  - QSPI/QSPI_PreInitConfig/Src/stm32f4xx_hal_msp.c  HAL MSP file    


@par Hardware and Software environment

  - This example runs on STM32F412xG devices.

  - This example has been tested with STM32412G-DISCOVERY board and can be
    easily tailored to any other supported device and development board.

  - STM32412G-DISCOVERY Set-up :
    - Please ensure that jumpers JP5 is fitted in position 1-2

  - A specific region for the QSPI memory has been added in the scatter file 
   (STM32F412xG_flash.icf for IAR toolchain, STM32412G-DISCOVERY.sct for Keil toolchain)
   in order to map functions in this memory

@par How to use it ? 

In order to make the program work, you must do the following :
 - Open your preferred toolchain
 - Rebuild all files 
 - Load your image into target memory with ST-Link Utility and external loader N25Q128A_STM32F412G-DISCO
   -> !!! Be careful, don't try to use the toolchain to load the image, it is not able to load some code in QSPI memory !!!
 - Run the example

 * <h3><center>&copy; COPYRIGHT STMicroelectronics</center></h3>
 */