57.7.8.6 Header Transmission (Host Node Configuration)

All LIN frames start with a header sent by the host node and consisting of a Synch Break Field, a Synch Field and an Identifier Field.

So in host node configuration, the frame handling starts with the sending of the header.

The header is transmitted as soon as the identifier is written in the LIN Identifier register (FLEX_US_LINIR). At this moment, the flag TXRDY falls.

The Break Field, the Synch Field and the Identifier Field are sent automatically one after the other.

The Break Field consists of 13 dominant bits and 1 recessive bit, the Synch Field is the character 0x55 and the Identifier corresponds to the character written in the LIN Identifier register (FLEX_US_LINIR). The Identifier parity bits can be automatically computed and sent (see Identifier Parity).

The flag TXRDY rises when the identifier character is transferred into the shift register of the transmitter.

As soon as the Synch Break Field is transmitted, the FLEX_US_CSR.LINBK flag bit is set. Likewise, as soon as the Identifier Field is sent, the FLEX_US_CSR.LINID flag bit is set. These flags are reset by writing a one to the FLEX_US_CR.RSTSTA bit.