uint8_t SPI_rx_data(void)
{
uint8_t data;
/* Tx a dummy data */
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
SPI_I2S_SendData(SPI1, data);
/* Wait for SPI1 data reception */
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
data = SPI_I2S_ReceiveData(SPI1);
return data;
}
I could find a data(0xff or 0x80) from the slave according to SCK when tranmit a dummy data.
But the master(STM32) does not have a valid data(0xff or 0x80) in the DR of SPI.
It has always 0x00 data.
So I have checked the following code, example code of SPI.
Also the DR of SPI has always 0x00 data.
int main(void)
{
/*!< At this stage the microcontroller clock setting is already configured,
this is done through SystemInit() function which is called from startup
file (startup_stm32f10x_xx.s) before to branch to application main.
To reconfigure the default setting of SystemInit() function, refer to
system_stm32f10x.c file
*/
/* System clocks configuration ---------------------------------------------*/
RCC_Configuration();
/* GPIO configuration ------------------------------------------------------*/
GPIO_Configuration();
/* SPI1 configuration ------------------------------------------------------*/
SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
SPI_InitStructure.SPI_DataSize = SPI_DataSize_16b;
SPI_InitStructure.SPI_CPOL = SPI_CPOL_Low;
SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;
SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_8;
SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
SPI_InitStructure.SPI_CRCPolynomial = 7;
SPI_Init(SPI1, &SPI_InitStructure);
/* SPI2 configuration ------------------------------------------------------*/
SPI_InitStructure.SPI_Mode = SPI_Mode_Slave;
SPI_Init(SPI2, &SPI_InitStructure);
/* Enable SPI1 CRC calculation */
SPI_CalculateCRC(SPI1, ENABLE);
/* Enable SPI2 CRC calculation */
SPI_CalculateCRC(SPI2, ENABLE);
/* Enable SPI1 */
SPI_Cmd(SPI1, ENABLE);
/* Enable SPI2 */
SPI_Cmd(SPI2, ENABLE);
/* Transfer procedure */
while (TxIdx < BufferSize - 1)
{
/* Wait for SPI1 Tx buffer empty */
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
/* Send SPI2 data */
SPI_I2S_SendData(SPI2, SPI2_Buffer_Tx[TxIdx]);
/* Send SPI1 data */
SPI_I2S_SendData(SPI1, SPI1_Buffer_Tx[TxIdx++]);
/* Wait for SPI2 data reception */
while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_RXNE) == RESET);
/* Read SPI2 received data */
SPI2_Buffer_Rx[RxIdx] = SPI_I2S_ReceiveData(SPI2);
/* Wait for SPI1 data reception */
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
/* Read SPI1 received data */
SPI1_Buffer_Rx[RxIdx++] = SPI_I2S_ReceiveData(SPI1);
}
/* Wait for SPI1 Tx buffer empty */
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
/* Wait for SPI2 Tx buffer empty */
while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_TXE) == RESET);
/* Send last SPI2_Buffer_Tx data */
SPI_I2S_SendData(SPI2, SPI2_Buffer_Tx[TxIdx]);
/* Enable SPI2 CRC transmission */
SPI_TransmitCRC(SPI2);
/* Send last SPI1_Buffer_Tx data */
SPI_I2S_SendData(SPI1, SPI1_Buffer_Tx[TxIdx]);
/* Enable SPI1 CRC transmission */
SPI_TransmitCRC(SPI1);
/* Wait for SPI1 last data reception */
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
/* Read SPI1 last received data */
SPI1_Buffer_Rx[RxIdx] = SPI_I2S_ReceiveData(SPI1);
/* Wait for SPI2 last data reception */
while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_RXNE) == RESET);
/* Read SPI2 last received data */
SPI2_Buffer_Rx[RxIdx] = SPI_I2S_ReceiveData(SPI2);
/* Wait for SPI1 data reception: CRC transmitted by SPI2 */
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
/* Wait for SPI2 data reception: CRC transmitted by SPI1 */
while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_RXNE) == RESET);
/* Check the received data with the send ones */
TransferStatus1 = Buffercmp(SPI2_Buffer_Rx, SPI1_Buffer_Tx, BufferSize);
TransferStatus2 = Buffercmp(SPI1_Buffer_Rx, SPI2_Buffer_Tx, BufferSize);
/* TransferStatus1, TransferStatus2 = PASSED, if the data transmitted and received
are correct */
/* TransferStatus1, TransferStatus2 = FAILED, if the data transmitted and received
are different */
/* Test on the SPI1 CRC Error flag */
if ((SPI_I2S_GetFlagStatus(SPI1, SPI_FLAG_CRCERR)) == SET)
{
TransferStatus2 = FAILED;
}
/* Test on the SPI2 CRC Error flag */
if ((SPI_I2S_GetFlagStatus(SPI2, SPI_FLAG_CRCERR)) == SET)
{
TransferStatus1 = FAILED;
}
/* Read SPI1 received CRC value */
CRC1Value = SPI_I2S_ReceiveData(SPI1);
/* Read SPI2 received CRC value */
CRC2Value = SPI_I2S_ReceiveData(SPI2);
while (1)
{}
}
/**
* @brief Configures the different system clocks.
* @param None
* @retval None
*/
void RCC_Configuration(void)
{
/* PCLK2 = HCLK/2 */
RCC_PCLK2Config(RCC_HCLK_Div2);
/* Enable peripheral clocks --------------------------------------------------*/
/* GPIOA, GPIOB and SPI1 clock enable */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB |
RCC_APB2Periph_SPI1, ENABLE);
/* SPI2 Periph clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);
}
/**
* @brief Configures the different GPIO ports.
* @param None
* @retval None
*/
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/* Configure SPI1 pins: SCK, MISO and MOSI ---------------------------------*/
/* Confugure SCK and MOSI pins as Alternate Function Push Pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_7;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Confugure MISO pin as Input Floating */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Configure SPI2 pins: SCK, MISO and MOSI ---------------------------------*/
/* Confugure SCK and MOSI pins as Input Floating */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13 | GPIO_Pin_15;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOB, &GPIO_InitStructure);
/* Confugure MISO pin as Alternate Function Push Pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOB, &GPIO_InitStructure);
}
Why the DR of SPI has always 0x00 data ?
Are there any problem in these codes ?
Thanks