title: Reading internal flash memory contens
body: <p>could someone please give a hint on how to read from flash.
  I have tried to set value inside flash and then read it afterwards inside the code.</p>
  
  <p>Inside ld file I have done following.</p>
  
  <pre><code>/* Specify the memory areas */
  MEMORY
  {
  FLASH (rx)      : ORIGIN = 0x8000000, LENGTH = 2048K
  RAM (xrw)      : ORIGIN = 0x20000000, LENGTH = 192K
  CCMRAM (rw)      : ORIGIN = 0x10000000, LENGTH = 64K
  DATA (rwx)        : ORIGIN = 0x080E0000, LENGTH = 128k
  }
  
  /* Define output sections */
  SECTIONS
  {
      .user_data :
      {
        . = ALIGN(4);
           *(.user_data)
        . = ALIGN(4);
      } &gt; DATA
  </code></pre>
  
  <p>Inside the code I set memory location to value of 1.
  Then try to use that value to blink led.</p>
  
  <pre><code>/**
    ******************************************************************************
    * File Name          : main.c
    * Description        : Main program body
    ******************************************************************************
    *
    * COPYRIGHT(c) 2016 STMicroelectronics
    *
    * 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.
    *
    ******************************************************************************
    */
  /* Includes ------------------------------------------------------------------*/
  #include "stm32f4xx_hal.h"
  #include "gpio.h"
  
  /* USER CODE BEGIN Includes */
  
  /* USER CODE END Includes */
  
  /* Private variables ---------------------------------------------------------*/
  
  /* USER CODE BEGIN PV */
  /* Private variables ---------------------------------------------------------*/
  __attribute__((__section__(".user_data"))) const uint8_t userConfig[64];
  /* USER CODE END PV */
  
  /* Private function prototypes -----------------------------------------------*/
  void SystemClock_Config(void);
  
  /* USER CODE BEGIN PFP */
  /* Private function prototypes -----------------------------------------------*/
  void write_data_to_flash(uint8_t address, uint32_t data){
      HAL_FLASH_Unlock();
  
        __HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_EOP | FLASH_FLAG_OPERR | FLASH_FLAG_WRPERR | FLASH_FLAG_PGAERR | FLASH_FLAG_PGSERR );
  
       FLASH_Erase_Sector(FLASH_SECTOR_11, VOLTAGE_RANGE_3);
  
  
        HAL_FLASH_Program(TYPEPROGRAM_BYTE, &amp;userConfig[address], 1);
  
        HAL_FLASH_Lock();
  }
  
  
  /* USER CODE END PFP */
  
  /* USER CODE BEGIN 0 */
  
  /* USER CODE END 0 */
  
  int main(void)
  {
  
    /* USER CODE BEGIN 1 */
      uint8_t pause;
    /* USER CODE END 1 */
  
    /* MCU Configuration----------------------------------------------------------*/
  
    /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
    HAL_Init();
  
    /* Configure the system clock */
    SystemClock_Config();
  
    /* Initialize all configured peripherals */
    MX_GPIO_Init();
  
    /* USER CODE BEGIN 2 */
  
   write_data_to_flash(0,0xAABBCCDD);
  //  write_data_to_flash(4,0xBBCCDDEE);
  //  write_data_to_flash(2,0xCC);
  //  write_data_to_flash(3,0xDD);
  
    pause = userConfig[0];
  
    /* USER CODE END 2 */
  
    /* Infinite loop */
    /* USER CODE BEGIN WHILE */
    while (1)
    {
    /* USER CODE END WHILE */
  
  
    /* USER CODE BEGIN 3 */
        HAL_GPIO_TogglePin(LD4_GPIO_Port,LD4_Pin);
        HAL_Delay(pause*1000);
  
    }
    /* USER CODE END 3 */
  
  }
  
  /** System Clock Configuration
  */
  void SystemClock_Config(void)
  {
  
    RCC_OscInitTypeDef RCC_OscInitStruct;
    RCC_ClkInitTypeDef RCC_ClkInitStruct;
  
    __HAL_RCC_PWR_CLK_ENABLE();
  
    __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE3);
  
    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
    RCC_OscInitStruct.HSIState = RCC_HSI_ON;
    RCC_OscInitStruct.HSICalibrationValue = 16;
    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
    RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
    RCC_OscInitStruct.PLL.PLLM = 8;
    RCC_OscInitStruct.PLL.PLLN = 50;
    RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
    RCC_OscInitStruct.PLL.PLLQ = 7;
    HAL_RCC_OscConfig(&amp;RCC_OscInitStruct);
  
    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                                |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
    RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
    RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
    RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
    HAL_RCC_ClockConfig(&amp;RCC_ClkInitStruct, FLASH_LATENCY_1);
  
    HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
  
    HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);
  
    /* SysTick_IRQn interrupt configuration */
    HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
  }
  
  /* USER CODE BEGIN 4 */
  
  /* USER CODE END 4 */
  
  #ifdef USE_FULL_ASSERT
  
  /**
     * @brief Reports the name of the source file and the source line number
     * where the assert_param error has occurred.
     * @param file: pointer to the source file name
     * @param line: assert_param error line source number
     * @retval None
     */
  void assert_failed(uint8_t* file, uint32_t line)
  {
    /* USER CODE BEGIN 6 */
    /* User can add his own implementation to report the file name and line number,
      ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
    /* USER CODE END 6 */
  
  }
  
  #endif
  
  /**
    * @}
    */ 
  
  /**
    * @}
  */ 
  
  /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
  </code></pre>