RM0444 Rev 5 1165/1390
RM0444 Serial peripheral interface / integrated interchip sound (SPI/I2S)
1195
If the SPI is disabled during a communication the following sequence must be followed:
1. Disable the SPI
2. Clear the CRCEN bit
3. Enable the CRCEN bit
4. Enable the SPI
Note: When the SPI interface is configured as a slave, the NSS internal signal needs to be kept
low during transaction of the CRC phase once the CRCNEXT signal is released. That is why
the CRC calculation cannot be used at NSS Pulse mode when NSS hardware mode should
be applied at slave normally.
At TI mode, despite the fact that clock phase and clock polarity setting is fixed and
independent on SPIx_CR1 register, the corresponding setting CPOL=0 CPHA=1 has to be
kept at the SPIx_CR1 register anyway if CRC is applied. In addition, the CRC calculation
has to be reset between sessions by SPI disable sequence with re-enable the CRCEN bit
described above at both master and slave side, else CRC calculation can be corrupted at
this specific mode.
35.6 SPI interrupts
During SPI communication an interrupt can be generated by the following events:
• Transmit TXFIFO ready to be loaded
• Data received in Receive RXFIFO
• Master mode fault
• Overrun error
• TI frame format error
•
CRC protocol error
Interrupts can be enabled and disabled separately.
Table 198. SPI interrupt requests
Interrupt event Event flag Enable Control bit
Transmit TXFIFO ready to be loaded TXE TXEIE
Data received in RXFIFO RXNE RXNEIE
Master Mode fault event MODF
ERRIE
Overrun error OVR
TI frame format error FRE
CRC protocol error CRCERR
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