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STM 32 interfacing EEPROM with SPI.

Question asked by kulshreshtha.samarth on Apr 15, 2014
Latest reply on Apr 15, 2014 by Clive One
I am using STM32f207IG.

/**
*****************************************************************************
**
**  File        : main.c
**
**  Abstract    : main function.
**
**  Functions   : main
**
**  Environment : Atollic TrueSTUDIO/STM32
**                STMicroelectronics STM32F2xx Standard Peripherals Library
**
**  Distribution: The file is distributed “as is,” without any warranty
**                of any kind.
**
**  (c)Copyright Atollic AB.
**  You may use this file as-is or modify it according to the needs of your
**  project. Distribution of this file (unmodified or modified) is not
**  permitted. Atollic AB permit registered Atollic TrueSTUDIO(R) users the
**  rights to distribute the assembled, compiled & linked contents of this
**  file as part of an application binary file, provided that it is built
**  using the Atollic TrueSTUDIO(R) toolchain.
**
**
*****************************************************************************
*/


/* Includes */
#include <stddef.h>
#include "stm32f2xx.h"




#ifdef USE_STM322xG_EVAL
 #include "stm322xg_eval.h"
 #include "stm322xg_eval_lcd.h"
 #include "stm322xg_eval_i2c_ee.h"
 #define USE_BOARD
 #define USE_LED
 #define USE_SEE
 #define USE_EVAL_AUDIO
#endif




/* Private typedef */
/* Private define  */
#ifdef USE_STM322xG_EVAL
  #define MESSAGE1   "  High-performance  "
  #define MESSAGE2   "    STM32 F-2       "
  #define MESSAGE3   "    running on      "
  #define MESSAGE4   "   STM3220F-EVAL    "
#endif
  #define MESSAGE5   " program built with "
  #define MESSAGE6   " Atollic TrueSTUDIO "




/* Private macro */
/* Private variables */
 USART_InitTypeDef USART_InitStructure;


/* Private function prototypes */
/* Private functions */


/**
**===========================================================================
**
**  Abstract: main program
**
**===========================================================================
*/




 void init_SPI1(void){


      GPIO_InitTypeDef GPIO_InitStruct;
      SPI_InitTypeDef SPI_InitStruct;


      // enable clock for used IO pins
      RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);


      /* configure pins used by SPI1
       * PA5 = SCK
       * PA6 = MISO
       * PA7 = MOSI
       * PB0 - CS
       * PB1 - HLD
       * PB2 - WP
       */
      GPIO_InitStruct.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_6 | GPIO_Pin_5;
      GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
      GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
      GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
      GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
      GPIO_Init(GPIOA, &GPIO_InitStruct);


      // connect SPI1 pins to SPI alternate function
      GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_SPI1);
      GPIO_PinAFConfig(GPIOA, GPIO_PinSource6, GPIO_AF_SPI1);
      GPIO_PinAFConfig(GPIOA, GPIO_PinSource7, GPIO_AF_SPI1);


      // enable clock for used IO pins
      RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);


      /* Configure the chip select pin
         in this case we will use PE7 */
      GPIO_InitStruct.GPIO_Pin =  GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2;
      GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;
      GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
      GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
      GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
      GPIO_Init(GPIOB, &GPIO_InitStruct);


      GPIOB->BSRRL |= GPIO_Pin_0; // set PB0 high
      GPIOB->BSRRL |= GPIO_Pin_0; // set PB1 high
      GPIOB->BSRRL |= GPIO_Pin_0; // set PB2 high




      // enable peripheral clock
      RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);


      /* configure SPI1 in Mode 0
       * CPOL = 0 --> clock is low when idle
       * CPHA = 0 --> data is sampled at the first edge
       */
      SPI_InitStruct.SPI_Direction = SPI_Direction_2Lines_FullDuplex; // set to full duplex mode, seperate MOSI and MISO lines
      SPI_InitStruct.SPI_Mode = SPI_Mode_Master;     // transmit in master mode, NSS pin has to be always high
      SPI_InitStruct.SPI_DataSize = SPI_DataSize_8b; // one packet of data is 8 bits wide
      SPI_InitStruct.SPI_CPOL = SPI_CPOL_Low;        // clock is low when idle
      SPI_InitStruct.SPI_CPHA = SPI_CPHA_1Edge;      // data sampled at first edge
      SPI_InitStruct.SPI_NSS = SPI_NSS_Soft | SPI_NSSInternalSoft_Set; // set the NSS management to internal and pull internal NSS high
      SPI_InitStruct.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_4; // SPI frequency is APB2 frequency / 4
      SPI_InitStruct.SPI_FirstBit = SPI_FirstBit_MSB;// data is transmitted MSB first
      SPI_Init(SPI1, &SPI_InitStruct);


      SPI_Cmd(SPI1, ENABLE); // enable SPI1
 }


 uint8_t SPI1_send(uint8_t data){


      SPI1->DR = data; // write data to be transmitted to the SPI data register
      while( !(SPI1->SR & SPI_I2S_FLAG_TXE) ); // wait until transmit complete
      while( !(SPI1->SR & SPI_I2S_FLAG_RXNE) ); // wait until receive complete
      while( SPI1->SR & SPI_I2S_FLAG_BSY ); // wait until SPI is not busy anymore
      return SPI1->DR; // return received data from SPI data register
 }


int main(void)
{
  int i = 0;


  /**
  *  IMPORTANT NOTE!
  *  The symbol VECT_TAB_SRAM needs to be defined when building the project
  *  if code has been located to RAM and interrupts are used. 
  *  Otherwise the interrupt table located in flash will be used.
  *  See also the <system_*.c> file and how the SystemInit() function updates 
  *  SCB->VTOR register.  
  *  E.g.  SCB->VTOR = 0x20000000;  
  */


  /* TODO - Add your application code here */


  uint8_t received_val = 0;
  uint8_t a1=0,a2=0;


       init_SPI1();


       while(1){


            GPIOB->BSRRH |= GPIO_Pin_0; // set PE7 (CS) low
            received_val=SPI1_send(0x05); //Read the status register
             GPIOB->BSRRL |= GPIO_Pin_0; // set PE7 (CS) high
       }




























#ifdef USE_LED
  /* Initialize LEDs */
  STM_EVAL_LEDInit(LED1);
  STM_EVAL_LEDInit(LED2);
  STM_EVAL_LEDInit(LED3);
  STM_EVAL_LEDInit(LED4);


  /* Turn on LEDs */
  STM_EVAL_LEDOn(LED1);
  STM_EVAL_LEDOn(LED2);
  STM_EVAL_LEDOn(LED3);
  STM_EVAL_LEDOn(LED4);


#endif


#ifdef USE_BOARD
  /* Initialize the LCD */
#ifdef USE_STM322xG_EVAL
  STM322xG_LCD_Init();
#endif


  /* Display message on STM3210X-EVAL LCD */
  /* Clear the LCD */
  LCD_Clear(White);


  /* Set the LCD Back Color */
  LCD_SetBackColor(Blue);
  /* Set the LCD Text Color */
  LCD_SetTextColor(White);
  LCD_DisplayStringLine(Line0, (uint8_t *)MESSAGE1);
  LCD_DisplayStringLine(Line1, (uint8_t *)MESSAGE2);
  LCD_DisplayStringLine(Line2, (uint8_t *)MESSAGE3);
  LCD_DisplayStringLine(Line3, (uint8_t *)MESSAGE4);
  LCD_DisplayStringLine(Line4, (uint8_t *)MESSAGE5);
  LCD_DisplayStringLine(Line5, (uint8_t *)MESSAGE6);


  /* USARTx configured as follow:
        - BaudRate = 115200 baud
        - Word Length = 8 Bits
        - One Stop Bit
        - No parity
        - Hardware flow control disabled (RTS and CTS signals)
        - Receive and transmit enabled
  */
  USART_InitStructure.USART_BaudRate = 115200;
  USART_InitStructure.USART_WordLength = USART_WordLength_8b;
  USART_InitStructure.USART_StopBits = USART_StopBits_1;
  USART_InitStructure.USART_Parity = USART_Parity_No;
  USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
  USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;


  STM_EVAL_COMInit(COM1, &USART_InitStructure);
#endif


  /* Infinite loop */
  while (1)
  {
     i++;
#ifdef USE_LED
     STM_EVAL_LEDToggle(LED1);
#endif
  }
}


#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 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) */


  /* Infinite loop */
  while (1)
  {
  }
}
#endif


/*
 * Minimal __assert_func used by the assert() macro
 * */
void __assert_func(const char *file, int line, const char *func, const char *failedexpr)
{
  while(1)
  {}
}


/*
 * Minimal __assert() uses __assert__func()
 * */
void __assert(const char *file, int line, const char *failedexpr)
{
   __assert_func (file, line, NULL, failedexpr);
}


#ifdef USE_SEE
#ifndef USE_DEFAULT_TIMEOUT_CALLBACK
/**
  * @brief  Basic management of the timeout situation.
  * @param  None.
  * @retval sEE_FAIL.
  */
uint32_t sEE_TIMEOUT_UserCallback(void)
{
  /* Return with error code */
  return sEE_FAIL;
}
#endif
#endif /* USE_SEE */


#ifdef USE_EVAL_AUDIO
/**
  * @brief  Basic management of the timeout situation.
  * @param  None.
  * @retval sEE_FAIL.
  */
void EVAL_AUDIO_TransferComplete_CallBack(uint32_t pBuffer, uint32_t Size)


{
  /* TODO, implement your code here */
  return;
}
#endif /* USE_EVAL_AUDIO */


When I am trying to interface the board with the EEPROM and read the status register I get a '0'. However, whenever I re run the same code the value that is initially there in the received_val is '224'. 

When I run the code and make received_val  '0', how come it becomes '224' when I re run the code? Does that mean that my code works?(I am trying to read the status register of the EEPROM)

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