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Serial peripheral interface (SPI) RM0090

908/1731 DocID018909 Rev 11

Overrun flag (OVR)

This flag is set when data are received and the previous data have not yet been read from

SPI_DR. As a result, the incoming data are lost. An interrupt may be generated if the ERRIE

bit is set in SPI_CR2.

In this case, the receive buffer contents are not updated with the newly received data from

the transmitter device. A read operation to the SPI_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 SPI_DR register followed by a read

access to the SPI_SR register.

Frame error flag (FRE)

This flag can be set by hardware only if the I2S is configured in Slave mode. It is set if the

external master is changing the WS line at a moment when the slave is not expected this

change. If the synchronization is lost, to recover from this state and resynchronize the

external master device with the I2S slave device, follow the steps below:

1. Disable the I2S

2. Re-enable it when the correct level is detected on the WS line (WS line is high in I2S

mode, or low for MSB- or LSB-justified or PCM modes).

Desynchronization between the master and slave device may be due to noisy environment

on the SCK 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.

28.4.9 I

S interrupts

Table 127 provides the list of I

S interrupts.

28.4.10 DMA features

DMA is working in exactly the same way as for the SPI mode. There is no difference on the

S. Only the CRC feature is not available in I

S mode since there is no data transfer

protection system.

Table 127. I

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 ERRIE

STMicroelectronics STM32F405 User Manual

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