Atmel Evaluation Kit AT91SAM9M10-G45-EK AT91SAM9M10-G45-EK Data Sheet
Product codes
AT91SAM9M10-G45-EK
519
SAM9M10 [DATASHEET]
6355F–ATARM–12-Mar-13
31.7.8.26
Bus Idle Time-out
If the LIN bus is inactive for a certain duration, the slave nodes shall automatically enter in sleep mode. In the LIN
2.0 specification, this time-out is fixed at 4 seconds. In the LIN 1.3 specification, it is fixed at 25000 Tbits.
2.0 specification, this time-out is fixed at 4 seconds. In the LIN 1.3 specification, it is fixed at 25000 Tbits.
In Slave Node configuration, the Receiver Time-out detects an idle condition on the RXD line. When a time-out is
detected, the bit TIMEOUT in the Channel Status Register (US_CSR) rises and can generate an interrupt, thus
indicating to the driver to go into sleep mode.
detected, the bit TIMEOUT in the Channel Status Register (US_CSR) rises and can generate an interrupt, thus
indicating to the driver to go into sleep mode.
The time-out delay period (during which the receiver waits for a new character) is programmed in the TO field of
the Receiver Time-out Register (US_RTOR). If the TO field is programmed at 0, the Receiver Time-out is disabled
and no time-out is detected. The TIMEOUT bit in US_CSR remains at 0. Otherwise, the receiver loads a 17-bit
counter with the value programmed in TO. This counter is decremented at each bit period and reloaded each time
a new character is received. If the counter reaches 0, the TIMEOUT bit in the Status Register rises.
the Receiver Time-out Register (US_RTOR). If the TO field is programmed at 0, the Receiver Time-out is disabled
and no time-out is detected. The TIMEOUT bit in US_CSR remains at 0. Otherwise, the receiver loads a 17-bit
counter with the value programmed in TO. This counter is decremented at each bit period and reloaded each time
a new character is received. If the counter reaches 0, the TIMEOUT bit in the Status Register rises.
If STTTO is performed, the counter clock is stopped until a first character is received.
If RETTO is performed, the counter starts counting down immediately from the value TO.
31.7.9
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.
on-board diagnostics. In the loopback mode the USART interface pins are disconnected or not and reconfigured
for loopback internally or externally.
31.7.9.1
Normal Mode
Normal mode connects the RXD pin on the receiver input and the transmitter output on the TXD pin.
Figure 31-55.
Normal Mode Configuration
31.7.9.2
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
pin, as shown in
nected to the receiver input, thus the receiver remains active.
Table 31-16.
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