Figure 473. Overrun Detection Error; Figure 474. Fifo Underrun Event - ST STM32L4 5 Series Reference Manual

Serial audio interface (SAI)
The OVRUDR flag is cleared when COVRUDR bit is set in the SAI_xCLRFR register.
Underrun
An underrun may occur when the audio block in the SAI is a transmitter and the FIFO is
empty when data need to be transmitted. If an underrun is detected, the slot number for
which the event occurs is stored and MUTE value (00) is sent until the FIFO is ready to
transmit the data corresponding to the slot for which the underrun was detected (refer to
Figure 474). This avoids desynchronization between the memory pointer and the slot in the
audio frame.
The underrun event sets the OVRUDR flag in the SAI_xSR register and an interrupt is
generated if the OVRUDRIE bit is set in the SAI_xIM register. To clear this flag, set
COVRUDR bit in the SAI_xCLRFR register.
The underrun event can occur when the audio sub-block is configured as master or slave.
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Figure 473. Overrun detection error

Figure 474. FIFO underrun event

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