Figure 355. Slot Size Configuration With Fboff = 0 In Sai_Xslotr; Figure 356. First Bit Offset - ST STM32F423 Reference Manual

RM0430
It is possible to choose the position of the first data bit to transfer within the slots, this offset
is configured by bit FBOFF[5:0] in the SAI_xSLOTR register. 0 values will be injected in
transmitter mode from the beginning of the slot until this offset position is reached. In
reception, the bit in the offset phase is ignored. This feature targets the LSB justified
protocol (if the offset is equal to the slot size minus the data size).
It is mandatory to respect the following conditions in order to avoid bad SAI behavior:
FBOFF ≤ (SLOTSZ - DS),
DS ≤ SLOTSZ,
NBSLOT x SLOTSZ ≤ FRL (frame length),
The number of slots should be even when bit FSDEF in the SAI_xFRCR register is set.
In AC'97 (bit PRTCFG[1:0] = 10), the slot size is automatically set as defined in
Section 30.11.

Figure 355. Slot size configuration with FBOFF = 0 in SAI_xSLOTR

Figure 356. First bit offset

RM0430 Rev 8
Serial audio interface (SAI)
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