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This commit is contained in:
Gregory Nutt 2016-08-13 10:24:40 -06:00
parent 172761163b
commit eed5e41626
1 changed files with 28 additions and 5 deletions
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33
arch/arm/src/stm32/stm32_spi.c
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@ -603,6 +603,20 @@ static inline uint16_t spi_readword(FAR struct stm32_spidev_s *priv)
/* Then return the received byte */
#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.... The receiver then has to access both data frames by a single
* 16-bit read of SPIx_DR as a response to this single RXNE event. The RxFIFO
* threshold setting and the following read access must be always kept aligned
* at the receiver side, as data can be lost if it is not in line."
*/
/* REVISIT */
#endif
return spi_getreg(priv, STM32_SPI_DR_OFFSET);
}
@ -631,11 +645,20 @@ static inline void spi_writeword(FAR struct stm32_spidev_s *priv, uint16_t 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."
* 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...
*
* "A specific problem appears if an odd number of such "fit into one byte"
* data frames must be handled. On the transmitter side, writing the last
* data frame of any odd sequence with an 8-bit access to SPIx_DR is enough.
* ..."
*
* REVISIT: "...The receiver has to change the Rx_FIFO threshold level for the
* last data frame received in the odd sequence of frames in order to generate
* the RXNE event."
*/
if (priv->nbits < 9)