DocID018909 Rev 11 937/1731
RM0090 Serial audio interface (SAI)
957
Figure 293. Tristate on output data line in a protocol like I2S
If the TRIS bit in the SAI_xCR2 register is cleared, all the High impedance states on the SD
output line on Figure 292 and Figure 293 are replaced by a drive with a value of 0.
29.13 Error flags
The SAI embeds some error flags:
– FIFO overrun/underrun,
– Anticipated frame synchronization detection,
– Late frame synchronization detection,
– Codec not ready (AC’97 exclusively),
– Wrong clock configuration in master mode.
29.13.1 FIFO overrun/underrun (OVRUDR)
The FIFO Overrun/Underrun bit is called OVRUDR in the SAI_xSR register.
The overrun or underrun errors occupy the same bit since an audio block can be either
receiver or transmitter and each audio block in an SAI has its own SAI_xSR register.
Overrun
When the audio block is configured as receiver, an overrun condition may appear if data is
received in an audio frame when the FIFO is full and is not able to store the received data.
In this case, the received data is lost, the flag OVRUDR in the SAI_xSR register is set and
an interrupt is generated if bit OVRUDRIE is set in the SAI_xIM register. The slot number
from which the overrun occurs, is stored internally. No more data will be stored into the FIFO
until it becomes free to store new data. When the FIFO has at least one data free, the SAI
audio block receiver will store new data (from new audio frame) from the slot number which
VORW
069
6ORWVL]H GDWDVL]H
6ORWVL]H!GDWDVL]H
6'RXWSXW
SCK
3LOT/. 3LOT/&& 3LOT/.
3LOT/. 3LOT/&& 3LOT/.
$ATA $ATA
3LOT/. 3LOT/&& 3LOT/.
$ATA
VORW
6'RXWSXW
$ATA $ATA
3LOT/. 3LOT/&& 3LOT/.
$ATA $ATA $ATA
3LOT/. 3LOT/&& 3LOT/.
$ATA
VORW
6'RXWSXW
3LOT/. 3LOT/&& 3LOT/.
$ATA $ATAM
To Next Page
Loading...
Need help?
General
