AT91SAM7XC512_1 Datasheet, PDF (370/727 Pages) ATMEL Corporation – AT91 ARM Thumb-based Microcontrollers

Figure 31-28. Normal Mode Configuration
Receiver
RXD
Transmitter
TXD
31.6.8.2
Automatic Echo Mode
Automatic echo mode allows bit-by-bit retransmission. When a bit is received on the RXD pin, it
is sent to the TXD pin, as shown in Figure 31-29. Programming the transmitter has no effect on
the TXD pin. The RXD pin is still connected to the receiver input, thus the receiver remains
active.
Figure 31-29. Automatic Echo Mode Configuration
Receiver
RXD
Transmitter
TXD
31.6.8.3
Local Loopback Mode
Local loopback mode connects the output of the transmitter directly to the input of the receiver,
as shown in Figure 31-30. The TXD and RXD pins are not used. The RXD pin has no effect on
the receiver and the TXD pin is continuously driven high, as in idle state.
Figure 31-30. Local Loopback Mode Configuration
Receiver
RXD
Transmitter
TXD
1
31.6.8.4
Remote Loopback Mode
Remote loopback mode directly connects the RXD pin to the TXD pin, as shown in Figure 31-31.
The transmitter and the receiver are disabled and have no effect. This mode allows bit-by-bit
retransmission.
370 AT91SAM7XC512/256/128 Preliminary
6209F–ATARM–17-Feb-09