All the LIN frames start with a header which is sent by the master node and consists of a Synch Break Field, Synch Field and Identifier Field.
So in master 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 (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 (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, US_CSR.LINBK is set to ‘1’. Likewise, as soon as the Identifier Field is sent, US_CSR.LINID is set to ‘1’. These flags are reset by writing a ‘1’ to US_CR.RSTSTA.
