STM32F4-Discovery SPI LIS3DSH

Question

I was able to use the code below to init the SPI and read the values from accelerometer

    SPI_InitTypeDef SPI_InitTypeDefStruct;
    GPIO_InitTypeDef GPIO_InitTypeDefStruct;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOE , ENABLE);

    SPI_InitTypeDefStruct.SPI_Direction         = SPI_Direction_2Lines_FullDuplex;
    SPI_InitTypeDefStruct.SPI_Mode              = SPI_Mode_Master;
    SPI_InitTypeDefStruct.SPI_DataSize          = SPI_DataSize_8b;
    SPI_InitTypeDefStruct.SPI_CPOL              = SPI_CPOL_High;
    SPI_InitTypeDefStruct.SPI_CPHA              = SPI_CPHA_2Edge;
    SPI_InitTypeDefStruct.SPI_NSS               = SPI_NSS_Soft | SPI_NSSInternalSoft_Set;
    SPI_InitTypeDefStruct.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256;     //seems like it was here causing trouble
    SPI_InitTypeDefStruct.SPI_FirstBit          = SPI_FirstBit_MSB;
    SPI_Init(SPI1, &SPI_InitTypeDefStruct);

    GPIO_InitTypeDefStruct.GPIO_Pin   = GPIO_Pin_5 | GPIO_Pin_7 | GPIO_Pin_6;
    GPIO_InitTypeDefStruct.GPIO_Mode  = GPIO_Mode_AF;
    GPIO_InitTypeDefStruct.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitTypeDefStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_InitTypeDefStruct.GPIO_PuPd  = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOA, &GPIO_InitTypeDefStruct);

    GPIO_InitTypeDefStruct.GPIO_Pin   = GPIO_Pin_3;
    GPIO_InitTypeDefStruct.GPIO_Mode  = GPIO_Mode_OUT;
    GPIO_InitTypeDefStruct.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitTypeDefStruct.GPIO_PuPd  = GPIO_PuPd_UP;
    GPIO_InitTypeDefStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_Init(GPIOE, &GPIO_InitTypeDefStruct);

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_SPI1);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource6, GPIO_AF_SPI1);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource7, GPIO_AF_SPI1);

    GPIO_SetBits(GPIOE, GPIO_Pin_3);
    SPI_Cmd(SPI1, ENABLE);

    SPI_send(0x23, 0xc9);                         // resetting the accelerometer internal circuit
    //SPI_send(0x20, 0x67);                         // 100Hz data update rate, block data update disable, x/y/z enabled
    SPI_send(0x20, 0x97);
    //SPI_send(0x24, 0x20);                         // Anti aliasing filter bandwidth 800Hz, 16G (very sensitive), no self-test, 4-wire interface
    SPI_send(0x24, 0x00);                         // Anti aliasing filter bandwidth 800Hz, 2G ( sensitive  ??), no self-test, 4-wire interface
    SPI_send(0x10, 0x00);                         // Output(X) = Measurement(X) - OFFSET(X) * 32;
    SPI_send(0x11, 0x00);                         // Output(Y) = Measurement(Y) - OFFSET(Y) * 32;
    SPI_send(0x12, 0x00);                         // Output(Z) = Measurement(Z) - OFFSET(Z) * 32;

void SPI_send(uint8_t address, uint8_t data)
{
  GPIO_ResetBits(GPIOE, GPIO_Pin_3);

  while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
  SPI_I2S_SendData(SPI1, address);
  while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
  SPI_I2S_ReceiveData(SPI1);

  while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
  SPI_I2S_SendData(SPI1, data);
  while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
  SPI_I2S_ReceiveData(SPI1);

  GPIO_SetBits(GPIOE, GPIO_Pin_3);

}



uint8_t SPI_read(uint8_t address)
{
  GPIO_ResetBits(GPIOE, GPIO_Pin_3);
  address = 0x80 | address;                         // 0b10 - reading and clearing status

  while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
  SPI_I2S_SendData(SPI1, address);
  while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
  SPI_I2S_ReceiveData(SPI1);

  while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
  SPI_I2S_SendData(SPI1, 0x00);
  while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);

  GPIO_SetBits(GPIOE, GPIO_Pin_3);

  return SPI_I2S_ReceiveData(SPI1);
}

Then I combined these code with my project which has an 500Hz interrupt. It always work at first but if i unplug the board then plug it in again, SPI will only read zeros, even though the LIS3DSH still have readings(i used oscilloscope checked it). I had to download the shorter version of the project code( taking out most of the code in the interrupt) to get SPI to work properly again. I am using the Kickstart, size-limited IAR ewarm I thought it was because my code exceed the limit. But I did not get warning and my code was not more than 32kb.

I am just confused since it works until I unplug it. Could someone give me some suggestions? Thanks

Michael Wang Michael Wang · Accepted Answer · 2015-02-09T22:19:07

I decided just to add the SPI_DeInit(...) before SPI_Init(...). This seems to solve the problem. I still dont understand why it wont reset itself though.

STM32F4-Discovery SPI LIS3DSH

1 Answers