SPI Read is not working

[Rahul5214]

I'm using this library for STM8S103F3to read LIS3DHaccelerometer. I wrote a spi read function in stdafx.c file as pasted below.

uint8_t spi_read_data_1_byte(uint8_t ReadAddr){
    uint8_t data;
    // PA3 = SS pin on STM8S103F3
    GPIO_WriteHigh(GPIOA, GPIO_PIN_3);  // SS pin Low
        //Send Address
        SPI_SendData(ReadAddr | 0x80); // MSB bit high for read mode
    data = SPI_ReceiveData();
    GPIO_WriteLow(GPIOA, GPIO_PIN_3);  // SS pin High
    return data;
}

But spi_read_data_1_byte always returns 255 value for all registers addresses.

I am using IAR and printf for debugging. I have cross checked SPI connections also and I can't figure the problem.

[pixma]

Some steps to diagnose -

• Check LIS3DH SPI Mode, please check the datasheet, maybe Mode 2, CPOL=1, CPHA=0.
• Check the circuit, LIS3DH should be configured for 3 Wire communication at least.

You can share your SPI Init code here for further investigation. And, SPI related functions and codes should not be in stdafx.c, it should be inside spi-related src files. "stdafx" is usually used for standard application framework purpose to include the basic framework or say header files into the project.

Keep me posted!

[Rahul5214]

I have tried all 4 SPI modes. Connection are as follows: full duplex mode STM -> LIS3DH PC7 -> SDO PC6 -> SDA, SDI PC5 -> SCL, SCK PA3 -> CS

SPI_Init(SPI_FIRSTBIT_MSB, SPI_BAUDRATEPRESCALER_8, SPI_MODE_MASTER, SPI_CLOCKPOLARITY_HIGH, SPI_CLOCKPHASE_2EDGE,SPI_DATADIRECTION_2LINES_FULLDUPLEX, SPI_NSS_SOFT,0x07);

GPIO_Init(GPIOA, GPIO_PIN_3, GPIO_MODE_OUT_PP_HIGH_SLOW); // SS pin = PA3 in STM8S103F3

void spi_read_data_1_byte( uint8_t ReadAddr){     // in stdafx.c file
    uint8_t data;
    GPIO_WriteLow(GPIOA, GPIO_PIN_3);

    /*!< Wait until the transmit buffer is empty */
    while (SPI_GetFlagStatus(SPI_FLAG_TXE) == RESET){}

    //Send Address
    SPI_SendData(ReadAddr | 0x80);   // MSB 1 for reading
    data = SPI_ReceiveData();
    printf("f- %d\n", data);
    SPI_SendData(0);
    data = SPI_ReceiveData();
    printf("s- %d\n", data);
    GPIO_WriteHigh(GPIOA, GPIO_PIN_3);
}

Code in main.c file

#include "stdafx.h"

void delay(uint16_t time){
    uint16_t i;
        uint16_t j;
    for (i=0; i<200; i++){
          for(j=0; j<time;j++){
            nop();
          }

    }
}
int main( void ){
    //GPIO_DeInit(GPIOB);
   // SPI_DeInit();

    //GPIO_Init(GPIOB, GPIO_PIN_5, GPIO_MODE_OUT_PP_LOW_FAST);
    init_spi();

    // The main loop
    while( 1 ){
        delay(80);
      //  GPIO_WriteReverse(GPIOB, GPIO_PIN_5);
        spi_read_data_1_byte(0x0f);//Random Address 0x40 for now.
    }
}

I have just edited stdafx.h and stdafx.c. All other files are untouched. Output in Terminal I\O

f- 0
s- 255
f- 51
s- 255
f- 51
s- 255
f- 51
s- 255

SPI register values after executing SPI_Init() function.

Reset value of SPI_DRis 0x00 but I don't know why it is showing blank in register window.

[Rahul5214]

Finally it worked with these changes.

SPI_Init(SPI_FIRSTBIT_MSB, SPI_BAUDRATEPRESCALER_8, SPI_MODE_MASTER, SPI_CLOCKPOLARITY_HIGH, SPI_CLOCKPHASE_2EDGE,SPI_DATADIRECTION_2LINES_FULLDUPLEX, SPI_NSS_SOFT,0x07); // in stafx.c

uint8_t SPI_read(uint8_t ReadAddr){
   uint8_t value;
   GPIO_WriteLow(GPIOA, GPIO_PIN_3);
   SPI_Transfer(ReadAddr | 0x80);
   value = SPI_Transfer(0);
   GPIO_WriteHigh(GPIOA, GPIO_PIN_3);
   return value;
}

void SPI_write(uint8_t WriteAddr, uint8_t value){
  GPIO_WriteLow(GPIOA, GPIO_PIN_3);
  SPI_Transfer(WriteAddr & ~0x80); // MSB 0 for writing
  SPI_Transfer(value);
  GPIO_WriteHigh(GPIOA, GPIO_PIN_3);
}

// in stm8s_spi.c

uint8_t SPI_Transfer(uint8_t Data){
    while (SPI_GetFlagStatus(SPI_FLAG_TXE) == RESET){}
    SPI->DR = Data;

    while (SPI_GetFlagStatus(SPI_FLAG_RXNE) == RESET){}
    return ((uint8_t)SPI->DR); /* Return the data in the DR register*/
}