Техническая Спецификация для Atmel Evaluation Kit AT91SAM9G25-EK AT91SAM9G25-EK
Модели
AT91SAM9G25-EK
820
SAM9G25 [DATASHEET]
11032C–ATARM–25-Jan-13
If RETTO is performed, the counter starts counting down immediately from the value TO.
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
39.7.9.3 Local Loopback Mode
Local loopback mode connects the output of the transmitter directly to the input of the receiver, as shown in
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.
high, as in idle state.
Table 39-16. 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