Posted on April 25, 2015 at 01:18Hi,
I modify the spi sample code but enable CRC function, however I always get CRCERR. I dont know the reason.
Here is the initialization of SPI: SPI2->CR1 |= SPI_BAUDRATEPRESCALER_256;
SPI2->CR1 &= ~SPI_CR1_CPOL;
SPI2->CR1 &= ~SPI_CR1_CPHA;
SPI2->CR1 &= ~SPI_CR1_BIDIMODE;
SPI2->CR1 |= SPI_CR1_CRCEN;
SPI2->CR1 &= ~SPI_CR1_RXONLY;
SPI2->CR1 |= SPI_CR1_SSM;
SPI2->CR1 |= SPI_CR1_SSI;
SPI2->CR1 &= ~SPI_CR1_LSBFIRST;
SPI2->CR1 |= SPI_CR1_MSTR;
SPI2->CR1 &= ~SPI_CR1_DFF;
/* Configure : NSS management */
SPI2->CR2 |= SPI_CR2_SSOE;
/* Configure : CRC Polynomial */
SPI2->CRCPR = 0x07; //reset value
Here is the Transmit function:
uint8_t SPI_Transmit(uint8_t *pData, uint16_t Size, uint32_t Timeout)
{
__IO uint16_t tmpreg;
uint8_t* pTxBuffPtr = pData;
uint16_t TxCount = Size;
if(SPI_State == SPI_STATE_READY)
{
if((pTxBuffPtr == NULL ) || (TxCount == 0))
{
return STATUS_ERROR;
}
SPI_State = SPI_STATE_BUSY_TX;
/* Reset CRC Calculation */
if(SPI2->CR1 & SPI_CR1_CRCEN)
{
SPI2->CR1 &= ~SPI_CR1_CRCEN;
SPI2->CR1 |= SPI_CR1_CRCEN;
}
/* Check if the SPI is already enabled */
if((SPI2->CR1 & SPI_CR1_SPE) != SPI_CR1_SPE)
{
/* Enable SPI peripheral */
SPI2->CR1 |= SPI_CR1_SPE;
}
if(TxCount == 0x01)
{
SPI2->DR = *pTxBuffPtr++;
TxCount--;
}
while(TxCount > 0)
{
/* Wait until TXE flag is set to send data */
if(SPI_WaitOnFlagUntilTimeout(SPI_SR_TXE, RESET, Timeout) != STATUS_OK)
{
return STATUS_TIMEOUT;
}
SPI2->DR = *pTxBuffPtr++;
TxCount--;
}
/* Enable CRC Transmission */
if(SPI2->CR1 & SPI_CR1_CRCEN)
{
SPI2->CR1 |= SPI_CR1_CRCNEXT;
}
/* Wait until TXE flag is set to send data */
if(SPI_WaitOnFlagUntilTimeout(SPI_SR_TXE, RESET, Timeout) != STATUS_OK)
{
return STATUS_TIMEOUT;
}
/* Wait until Busy flag is reset before disabling SPI */
if(SPI_WaitOnFlagUntilTimeout(SPI_SR_BSY, SET, Timeout) != STATUS_OK)
{
return STATUS_TIMEOUT;
}
/* Clear OVERUN flag in 2 Lines communication mode because received is not read */
if((SPI2->CR1 & SPI_CR1_BIDIMODE) == 0)
{
tmpreg = SPI2->DR;
tmpreg = SPI2->SR;
}
SPI_State = SPI_STATE_READY;
return STATUS_OK;
}
else
{
return STATUS_BUSY;
}
}
After call this function, CRCERR bit will be set.
I enable CRCNEXT bit after last data is written to the SPI_DR register.
It should be ok right?
What is the problem? Please help me.
Thank you. #stm32 #crc #spi
