57.7.8.18 Bus Idle Timeout

If the LIN bus is inactive for a certain duration, the client nodes shall automatically enter in Sleep mode. In the LIN 2.0 specification, this timeout is defined as 4 seconds. In the LIN 1.3 specification, it is defined as 25,000 t_bit.

In client node configuration, the receiver timeout detects an idle condition on the RXD line. When a timeout is detected, the FLEX_US_CSR.TIMEOUT bit 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 the FLEX_US_RTOR.TO field. If a zero is written to the TO field, the Receiver Timeout is disabled and no timeout is detected. The FLEX_US_CSR.TIMEOUT bit 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 FLEX_US_CSR.TIMEOUT bit 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.