29.6.11 Loop-Back Mode

For debugging purposes, the I²S can be configured to loop back the Transmitter to the Receiver. Writing a '1' to the Loop-Back Test Mode bit in the Serializer m Control register (SERCTRLm.RXLOOP) configures SDm as input and the remaining SD as output. Both SD will be connected internally, so the transmitted data is also received. For instance, writing SERCTRL0.RXLOOP=1 will connect SD1 output to SD0 input, or writing SERCTRL1.RXLOOP=1 will connect SD0 output to SD1 input.

RXLOOP=1 will connect the Transmitter output of the other Serializer to the Receiver input of the current Serializer. For the Loop-back Mode to work, the current Serializer must be configured as receiver and the other Serializer as transmitter.

Writing SERCTRLm.RXLOOP=0 will restore normal behavior and connection between Serializer m and SDm pin input.

As for other changes to the Serializer configuration, Serializer m must be disabled before writing the SERCTRLm register to update SERCTRLm.RXLOOP.