Atmel Xplained Evaluation Board AT32UC3A3-XPLD AT32UC3A3-XPLD Data Sheet

32072H–AVR32–10/2012

Figure 25-52. ASK Modulator Output

Figure 25-53. FSK Modulator Output

The internal loopback feature enables on-board diagnostics, and allows the USART to operate
in three different test modes, with reconfigured pin functionality, as shown below. 

During normal operation, a receiver RXD pin is connected to a transmitter TXD pin.

Figure 25-54. Normal Mode Configuration

Automatic echo mode allows bit-by-bit retransmission. When a bit is received on the RXD pin, it
is also sent to the TXD pin, as shown in 

. Transmitter configuration has no effect.

Manchester

encoded

data

default polarity

unipolar output

Txd

ASK Modulator

Output

Uptstream Frequency F0

NRZ stream

1

0

0

1

Manchester

encoded

data

default polarity

unipolar output

Txd

FSK Modulator

Output

Uptstream Frequencies 

[F0, F0+offset]

NRZ stream

1

0

0

1

Receiver

Transmitter

RXD

TXD