Figure 325. Txe/Rxne/Bsy Behavior In Master / Full-Duplex Mode (Bidimode=0, Rxonly=0) In The Case Of Continuous Transfers - ST STM32F423 Reference Manual

RM0430 Serial peripheral interface/ inter-IC sound (SPI/I2S)
underflow error signal for slave operating in SPI mode, and that data from the slave are
always transacted and processed by the master even if the slave cannot not prepare them
correctly in time. It is preferable for the slave to use DMA, especially when data frames are
shorter and bus rate is high.
Each sequence must be encased by the NSS pulse in parallel with the multislave system to
select just one of the slaves for communication. In single slave systems, using NSS to
control the slave is not necessary. However, the NSS pulse can be used to synchronize the
slave with the beginning of each data transfer sequence. NSS can be managed either by
software or by hardware (see Section 29.3.4: Multi-master communication).
Refer to Figure 325 and Figure 326 for a description of continuous transfers in master / full-
duplex and slave full-duplex mode.
Figure 325. TXE/RXNE/BSY behavior in master / full-duplex mode (BIDIMODE=0,
RXONLY=0) in the case of continuous transfers
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