HI folks,
I am trying to read MEMS sensor through SPI. I am using Olimex’s STM32-H107(which uses STM32F107VC). When I read, it returns all FFs… I checked the chip select of SPI interface. It properly moves to low and high…So, the slave is selected properly. Here is how I configure SPI interface…I am running the MCU at 72MHz…If you guys can give some pointers, that would be great…
SPI_InitTypeDef SPI_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
/* Enable GPIO clock */
RCC_APB2PeriphClockCmd(R_ACC_SPI_GPIO_CLK | RCC_APB2Periph_AFIO, ENABLE);
/* Enable SPI clock */
RCC_APB1PeriphClockCmd(R_ACC_SPI_CLK, ENABLE);
/* Configure SPI pins: SCK, MISO and MOSI */
GPIO_InitStructure.GPIO_Pin = R_ACC_SPI_SCK_PIN | R_ACC_SPI_MISO_PIN | R_ACC_SPI_MOSI_PIN| R_ACC_SPI_NSS_PIN;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(R_ACC_SPI_GPIO_PORT, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = R_ACC_SPI_NSS_PIN;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(R_ACC_SPI_GPIO_PORT, &GPIO_InitStructure);
SPI_I2S_DeInit(R_ACC_SPI);
/* SPI Config */
SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;
SPI_InitStructure.SPI_CPOL = SPI_CPOL_High;
SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;
SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_64;
SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
SPI_Init(R_ACC_SPI, &SPI_InitStructure);
/* SPI enable */
SPI_Cmd(R_ACC_SPI, ENABLE);
GPIO_WriteBit(R_ACC_SPI_GPIO_PORT, R_ACC_SPI_NSS_PIN, Bit_SET);
GPIO_WriteBit(R_ACC_SPI_GPIO_PORT, R_ACC_SPI_SCK_PIN, Bit_RESET);
GPIO_WriteBit(R_ACC_SPI_GPIO_PORT, R_ACC_SPI_MISO_PIN, Bit_RESET);
GPIO_WriteBit(R_ACC_SPI_GPIO_PORT, R_ACC_SPI_MOSI_PIN, Bit_RESET);
My system_Init( ) is as follows - just to give you guys info on how I am configuring PLLs.
void SystemInit()
{
/* SYSCLK, HCLK, PCLK2 and PCLK1 configuration -----------------------------*/
/* RCC system reset(for debug purpose) */
RCC_DeInit();
/* Enable HSE */
RCC_HSEConfig(RCC_HSE_ON);
/* Wait till HSE is ready */
HSEStartUpStatus = RCC_WaitForHSEStartUp();
if (HSEStartUpStatus == SUCCESS)
{
/* Enable Prefetch Buffer */
FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
/* Flash 2 wait state */
FLASH_SetLatency(FLASH_Latency_2);
/* HCLK = SYSCLK */
RCC_HCLKConfig(RCC_SYSCLK_Div1);
/* PCLK2 = HCLK */
RCC_PCLK2Config(RCC_HCLK_Div1);
/* PCLK1 = HCLK/2 */
RCC_PCLK1Config(RCC_HCLK_Div2);
#ifdef STM32F10X_CL
/* Configure PLLs *********************************************************/
/* PLL2 configuration: PLL2CLK = (HSE / 5) * 8 = 40 MHz */
RCC_PREDIV2Config(RCC_PREDIV2_Div5);
RCC_PLL2Config(RCC_PLL2Mul_8);
/* Enable PLL2 */
RCC_PLL2Cmd(ENABLE);
/* Wait till PLL2 is ready */
while (RCC_GetFlagStatus(RCC_FLAG_PLL2RDY) == RESET)
{}
/* PLL configuration: PLLCLK = (PLL2 / 5) * 9 = 72 MHz */
RCC_PREDIV1Config(RCC_PREDIV1_Source_PLL2, RCC_PREDIV1_Div5);
RCC_PLLConfig(RCC_PLLSource_PREDIV1, RCC_PLLMul_9);
#else
/* PLLCLK = 8MHz * 9 = 72 MHz */
RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);
#endif
/* Enable PLL */
RCC_PLLCmd(ENABLE);
/* Wait till PLL is ready */
while (RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET)
{
}
/* Select PLL as system clock source */
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
/* Wait till PLL is used as system clock source */
while(RCC_GetSYSCLKSource() != 0x08)
{
}
}
else
{ /* If HSE fails to start-up, the application will have wrong clock configuration.
User can add here some code to deal with this error */
/* Go to infinite loop */
while (1)
{
}
}
SystemCoreClock = 72000000; // 72 Mhz
}