Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Data Sheet

799

SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]

11063K–ATARM–05-Nov-13

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 25,000 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.

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 a zero is written to the TO field, 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 US_CSR 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.

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. 

Normal mode connects the RXD pin on the receiver input and the transmitter output on the TXD pin.

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