I 2 S Error Flags - STMicroelectronics STM32F05 series Reference Manual

Serial peripheral interface / inter-IC sound (SPI/I2S)
Channel Side flag (CHSIDE)
In transmission mode, this flag is refreshed when TXE goes high. It indicates the channel
side to which the data to transfer on SD has to belong. In case of an underrun error event in
slave transmission mode, this flag is not reliable and I
switched on before resuming the communication.
In reception mode, this flag is refreshed when data are received into SPIx_DR. It indicates
from which channel side data have been received. Note that in case of error (like OVR) this
flag becomes meaningless and the I
(with configuration if it needs changing).
This flag has no meaning in the PCM standard (for both Short and Long frame modes).
When the OVR or UDR flag in the SPIx_SR is set and the ERRIE bit in SPIx_CR2 is also
set, an interrupt is generated. This interrupt can be cleared by reading the SPIx_SR status
register (once the interrupt source has been cleared).
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26.6.7 I S error flags
There are three error flags for the I
Underrun flag (UDR)
In slave transmission mode this flag is set when the first clock for data transmission appears
while the software has not yet loaded any value into SPIx_DR. It is available when the
I2SMOD bit in the SPIx_I2SCFGR register is set. An interrupt may be generated if the
ERRIE bit in the SPIx_CR2 register is set.
The UDR bit is cleared by a read operation on the SPIx_SR register.
Overrun flag (OVR)
This flag is set when data are received and the previous data have not yet been read from
the SPIx_DR register. As a result, the incoming data are lost. An interrupt may be generated
if the ERRIE bit is set in the SPIx_CR2 register.
In this case, the receive buffer contents are not updated with the newly received data from
the transmitter device. A read operation to the SPIx_DR register returns the previous
correctly received data. All other subsequently transmitted half-words are lost.
Clearing the OVR bit is done by a read operation on the SPIx_DR register followed by a read
access to the SPIx_SR register.
Frame error flag (FRE)
This flag can be set by hardware only if the I
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
1. Disable the I
2. Enable it again when the correct level is detected on the WS line (WS line is high in I
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 SCK communication clock or on the WS frame synchronization line. An error interrupt
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S should be reset by disabling and then enabling it
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S cell.
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S.
Doc ID 018940 Rev 1
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S needs to be switched off and
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S is configured in Slave mode. It is set if the
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S slave device:
RM0091
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S