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11028E–ATARM–22-Apr-13
SAM9G46
33.7.8.5
Header Transmission (Master Node Configuration)
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 charac-
ter 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
SectionThe 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 flag LINBK in the Channel Sta-
tus register (US_CSR) is set to “1”. Likewise, as soon as the Identifier Field is sent, the flag
LINID in the Channel Status register (US_CSR) is set to “1”. These flags are reset by writing the
bit RSTSTA at “1” in the Control register (US_CR).
Figure 33-40. Header Transmission
TXD
Baud Rate
Clock
Start
Bit
Write
US_LINIR
10101010
TXRDY
Stop
Bit
Start
Bit
ID0
ID1
ID2
ID3
ID4
ID5
ID6
ID7
Break Field
13 dominant bits (at 0)
Stop
Bit
Break
Delimiter
1 recessive bit
(at 1)
Synch Byte = 0x55
US_LINIR
ID
LINID
in US_CSR
LINBK
in US_CSR
Write RSTSTA=1
in US_CR