204
ATmega16M1/32M1/64M1 [DATASHEET]
8209E–AVR–11/2012
20.5.11
Break-in-data
According to the LIN protocol, the LIN/UART controller can detect the BREAK/SYNC field sequence even if the
break is partially superimposed with a byte of the response. When a BREAK/SYNC field sequence happens, the
transfer in progress is aborted and the processing of the new frame starts.
On slave node(s), an error is generated (that is, LBERR in case of Tx Response or LFERR in case of Rx
On master node, the user (code) is responsible for this aborting of frame. To do this, the master task has first to
abort the on-going communication (clearing LCMD bits - LIN Abort command) and then to apply the Tx Header
command. In this case, the abort error flag - LABORT - is set
On the slave node, the BREAK detection is processed with the synchronization setting available when the
LIN/UART controller processed the (aborted) response. But the re-synchronization restarts as usual. Due to a pos-
sible difference of timing reference between the BREAK field and the rest of the frame, the time-out values can be
slightly inaccurate.
20.5.12
Checksum
The last field of a frame is the checksum.
In LIN 2.1, the checksum contains the inverted eight bit sum with carry over all data bytes and the protected identi-
fier. This calculation is called enhanced checksum.
In LIN 1.3, the checksum contains the inverted eight bit sum with carry over all data bytes. This calculation is called
classic checksum.
Frame identifiers 60 (0x3C) to 61 (0x3D) shall always use classic checksum.
20.5.13
Interrupts
As shown in
Figure 20-13, the four communication flags of the LINSIR register are combined to drive two inter-
rupts. Each of these flags have their respective enable interrupt bit in LINENIR register.
CHECKSUM
255
unsigned char
DATA
n
0
n
PROTECTED ID.
+
unsigned char
DATA
n
0
n
PROTECTED ID.
+
8
+
–
=
CHECKSUM
255
unsigned char
DATA
n
0
n
unsigned char
DATA
n
0
n
8
+
–
=