Atmel Evaluation Kit AT91SAM9X25-EK AT91SAM9X25-EK Data Sheet
Product codes
AT91SAM9X25-EK
836
SAM9X25 [DATASHEET]
11054E–ATARM–10-Mar-2014
.
39.7.9 Test Modes
The USART can be programmed to operate in three different test modes. The internal loopback capability allows on-
board diagnostics. In the loopback mode the USART interface pins are disconnected or not and reconfigured for
loopback internally or externally.
board diagnostics. In the loopback mode the USART interface pins are disconnected or not and reconfigured for
loopback internally or externally.
39.7.9.1 Normal Mode
Normal mode connects the RXD pin on the receiver input and the transmitter output on the TXD pin.
Figure 39-54.Normal Mode Configuration
39.7.9.2 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
shown in
. 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 39-55.Automatic Echo Mode Configuration
Receiver Time-out programming
LIN Specification
Baud Rate
Time-out period
TO
2.0
1 000 bit/s
4s
4 000
2 400 bit/s
9 600
9 600 bit/s
38 400
19 200 bit/s
76 800
20 000 bit/s
80 000
1.3
-
25 000 Tbits
25 000
Receiver
Transmitter
RXD
TXD
Receiver
Transmitter
RXD
TXD