NXP Semiconductors QorIQ LS1012A Reference Manual

Figure 22-3. SAI first bit shifted, MSB first22.5.5.2 FIFO pointersWhen writing to a TDR, the WFP of the corresponding TFR increments after each validwrite. The SAI supports 8-bit, 16-bit and 32-bit writes to the TDR and the FIFO pointerwill increment after each individual write. Note that 8-bit writes should only be usedwhen transmitting up to 8-bit data and 16-bit writes should only be used whentransmitting up to 16-bit data.Writes to a TDR are ignored if the corresponding bit of TCR3[TCE] is clear or if theFIFO is full. If the Transmit FIFO is empty, the TDR must be written at least three bitclocks before the start of the next unmasked word to avoid a FIFO underrun.When reading an RDR, the RFP of the corresponding RFR increments after each validread. The SAI supports 8-bit, 16-bit and 32-bit reads from the RDR and the FIFO pointerwill increment after each individual read. Note that 8-bit reads should only be used whenreceiving up to 8-bit data and 16-bit reads should only be used when receiving up to 16-bit data.Reads from an RDR are ignored if the corresponding bit of RCR3[RCE] is clear or if theFIFO is empty. If the Receive FIFO is full, the RDR must be read at least three bit clocksbefore the end of an unmasked word to avoid a FIFO overrun.Functional descriptionQorIQ LS1012A Reference Manual, Rev. 1, 01/20181074 NXP Semiconductors