SAM4L Datasheet, PDF (611/1185 Pages) ATMEL Corporation – ATSAM ARM-based Flash MCU

Figure 24-52. ASK Modulator Output
1
0
NRZ stream
Manchester
encoded
data
default polarity
Txd
unipolar output
ASK Modulator
Output
Uptstream Frequency F0
Figure 24-53. FSK Modulator Output
1
0
NRZ stream
Manchester
encoded
data
Txd
default polarity
unipolar output
FSK Modulator
Output
Uptstream Frequencies
[F0, F0+offset]
ATSAM4L4/L2
0
1
0
1
24.6.17 Test Modes
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.
24.6.17.1 Normal Mode
During normal operation, a receiver RXD pin is connected to a transmitter TXD pin.
Figure 24-54. Normal Mode Configuration
Receiver
RXD
Transmitter
TXD
24.6.17.2
Automatic Echo Mode
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 Figure 24-55. Transmitter configuration has no effect.
42023C–SAM–02/2013
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