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RM0365
Serial peripheral interface / inter-IC sound (SPI/I2S)
959
Frame error flag (FRE)
This flag can be set by hardware only if the I
2
S is configured in Slave mode. It is set if the
external master is changing the WS line while the slave is not expecting this change. If the
synchronization is lost, the following steps are required to recover from this state and
resynchronize the external master device with the I
2
S slave device:
1.
Disable the I
2
S.
2. Enable it again when the correct level is detected on the WS line (WS line is high in I
2
S
mode or low for MSB- or LSB-justified or PCM modes.
Desynchronization between master and slave devices may be due to noisy environment on
the CK communication clock or on the WS frame synchronization line. An error interrupt can
be generated if the ERRIE bit is set. The desynchronization flag (FRE) is cleared by
software when the status register is read.
30.7.10 DMA
features
In I
2
S mode, the DMA works in exactly the same way as it does in SPI mode. There is no
difference except that the CRC feature is not available in I
2
S mode since there is no data
transfer protection system.
30.8 I
2
S interrupts
provides the list of I
2
S interrupts.
Table 165. I
2
S interrupt requests
Interrupt event
Event flag
Enable control bit
Transmit buffer empty flag
TXE
TXEIE
Receive buffer not empty flag
RXNE
RXNEIE
Overrun error
OVR
ERRIE
Underrun error
UDR
Frame error flag
FRE