Datasheet

29.6.11 Loop-Back Mode
For debugging purposes, the I
2
S 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.
29.7 I
2
S Application Examples
The I
2
S can support several serial communication modes used in audio or high-speed serial links. Some
standard applications are shown in the following figures.
Note: The following examples are not a complete list of serial link applications supported by the I
2
S.
Figure 29-7. Audio Application Block Diagram
Serial Clock
Word Select
Serial Data Out
MSB
Left Channel
LSB MSB
Right Channel
Serial Data Out
Word Select
Serial Clock
I
2
S
SCKn
FSn
SDOm
EXTERNAL
I
2
S
RECEIVER
SAM D21 Family
I2S - Inter-IC Sound Controller
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40001882D-page 640