ATtiny167-ESSZ datasheet(177/282 Pages) ATMEL

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177

7728D–AVR–07/09

ATtiny87/ATtiny167

15.5.10

Frame Time Out

According to the LIN protocol, a frame time-out error is flagged if: T

Frame > T Frame_Maximum.

This feature is implemented in the LIN/UART controller.

Figure 15-12. LIN timing and frame time-out

15.5.11

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 (i.e. LBERR in case of Tx Response or LFERR in

case of Rx Response). Information on data error is also available, refer to the Section

15.5.7.5.

• 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 avail-

able when the LIN/UART controller pr ocessed th e (abo rt ed ) re spon se. But th e

re-synchronization restarts as usual. Due to a possible difference of timing reference between

the BREAK field and the rest of the frame, the time-out values can be slightly inaccurate.

15.5.12

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 identifier. 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.

BREAK

Field

SYNC

Field

CHECKSUM

Field

DATA-0

Field

IDENTIFIER

PROTECTED

DATA-n

Field

T Response

T Header

T Frame

T Header_Maximum

T Header_Maximum + T Response_Maximum

1.4 x

T Header_Nominal

1.4 x

T Response_Nominal

T Response_Maximum

T Frame_Maximum

Maximun before Time-out

T Header_Nominal

T Header_Nominal + T Response_Nominal

34 x

T Bit

10 ( Number_of_Data + 1 ) x

T Bit

T Response_Nominal

T Frame_Nominal

Nominal

CHECKSUM

255

unsigned char

DATA n

∑

⎝⎠

⎜⎟

⎛⎞

PROTECTED ID.

⎝⎠

⎜⎟

⎛⎞

unsigned char

DATA n

∑

⎝⎠

⎜⎟

⎛⎞

PROTECTED ID.

⎝⎠

⎜⎟

⎛⎞

⎝⎠

⎜⎟

⎛⎞

⎝

⎠

⎜

⎟

⎜

⎟

⎛

⎞

–

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