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STM32F3 SPI: Cannot write 16-bit value to DR register because of how the F3 implements data packing.

This commit is contained in:
Gregory Nutt 2016-08-13 10:11:23 -06:00
parent 51fcd89b98
commit 172761163b
1 changed files with 47 additions and 2 deletions
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49
arch/arm/src/stm32/stm32_spi.c
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@ -195,6 +195,10 @@ struct stm32_spidev_s
static inline uint16_t spi_getreg(FAR struct stm32_spidev_s *priv, uint8_t offset);
static inline void spi_putreg(FAR struct stm32_spidev_s *priv, uint8_t offset,
uint16_t value);
#if defined(CONFIG_STM32_STM32F30XX) || defined(CONFIG_STM32_STM32F37XX)
static inline void spi_putreg8(FAR struct stm32_spidev_s *priv, uint8_t offset,
uint8_t value);
#endif
static inline uint16_t spi_readword(FAR struct stm32_spidev_s *priv);
static inline void spi_writeword(FAR struct stm32_spidev_s *priv, uint16_t byte);
static inline bool spi_16bitmode(FAR struct stm32_spidev_s *priv);
@ -553,6 +557,30 @@ static inline void spi_putreg(FAR struct stm32_spidev_s *priv, uint8_t offset, u
putreg16(value, priv->spibase + offset);
}
/************************************************************************************
* Name: spi_putreg8
*
* Description:
* Write an 8-bit value to the SPI register at offset
*
* Input Parameters:
* priv - private SPI device structure
* offset - offset to the register of interest
* value - the 16-bit value to be written
*
* Returned Value:
* The contents of the 16-bit register
*
************************************************************************************/
#if defined(CONFIG_STM32_STM32F30XX) || defined(CONFIG_STM32_STM32F37XX)
static inline void spi_putreg8(FAR struct stm32_spidev_s *priv, uint8_t offset,
uint8_t value)
{
putreg8(value, priv->spibase + offset);
}
#endif
/************************************************************************************
* Name: spi_readword
*
@ -599,9 +627,26 @@ static inline void spi_writeword(FAR struct stm32_spidev_s *priv, uint16_t word)
while ((spi_getreg(priv, STM32_SPI_SR_OFFSET) & SPI_SR_TXE) == 0);
/* Then send the byte */
/* Then send the word */
spi_putreg(priv, STM32_SPI_DR_OFFSET, word);
#if defined(CONFIG_STM32_STM32F30XX) || defined(CONFIG_STM32_STM32F37XX)
/* "When the data frame size fits into one byte (less than or equal to 8 bits),
* data packing is used automatically when any read or write 16-bit access is
* performed on the SPIx_DR register. The double data frame pattern is handled
* in parallel in this case. At first, the SPI operates using the pattern
* stored in the LSB of the accessed word, then with the other half stored in
* the MSB."
*/
if (priv->nbits < 9)
{
spi_putreg8(priv, STM32_SPI_DR_OFFSET, (uint8_t)word);
}
else
#endif
{
spi_putreg(priv, STM32_SPI_DR_OFFSET, word);
}
}
/************************************************************************************