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 timeout is fixed at 4 seconds. In the LIN 1.3 specification, it is fixed at 25,000 tbit.
In slave Node configuration, the receiver timeout detects an idle condition on the RXD line. When a timeout is detected, US_CSR.TIMEOUT rises and can generate an interrupt, thus indicating to the driver to go into Sleep mode.
The timeout delay period (during which the receiver waits for a new character) is programmed in US_RTOR.TO. If a ‘0’ is written to TO, the Receiver Timeout is disabled and no timeout is detected. US_CSR.TIMEOUT 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, US_CSR.TIMEOUT rises.
If US_CR.STTTO is written to ‘1’, the counter clock is stopped until a first character is received.
If US_CR.RETTO is written to ‘1’, the counter starts counting down immediately from the value TO.
| LIN Specification | Baud Rate | Timeout period | US_RTOR.TO |
|---|---|---|---|
| 2.0 | 1,000 bit/s | 4 s | 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 tbit | 25,000 |