Datasheet

733
SAM4S Series [DATASHEET]
11100F–ATARM–29-Jan-14
The local loopback mode allows the transmitted characters to be received. UTXD and URXD pins are not used and the
output of the transmitter is internally connected to the input of the receiver. The URXD pin level has no effect and the
UTXD line is held high, as in idle state.
The remote loopback mode directly connects the URXD pin to the UTXD line. The transmitter and the receiver are
disabled and have no effect. This mode allows a bit-by-bit retransmission.
Figure 35-11. Test Modes
Receiver
Transmitter
Disabled
RXD
TXD
Receiver
Transmitter
Disabled
RXD
TXD
V
DD
Disabled
Receiver
Transmitter
Disabled
RXD
TXD
Disabled
Automatic Echo
Local Loopback
Remote Loopback
V
DD