Atmel Evaluation Kit AT91SAM9M10-G45-EK AT91SAM9M10-G45-EK Data Sheet

 511

SAM9M10 [DATASHEET]

6355F–ATARM–12-Mar-13

The LIN response data length is the number of data fields (bytes) of the response excluding the checksum.

The response data length can either be configured by the user or be defined automatically by bits 4 and 5 of the
Identifier (compatibility to LIN Specification 1.1). The user can choose between these two modes by the DLM bit of
the LIN Mode register (US_LINMR):

• DLM = 0: the response data length is configured by the user via the DLC field of the LIN Mode register 

(US_LINMR). The response data length is equal to (DLC + 1) bytes. DLC can be programmed from 0 to 255, so 
the response can contain from 1 data byte up to 256 data bytes.

• DLM = 1: the response data length is defined by the Identifier (IDCHR in US_LINIR) according to the table 

below. The DLC field of the LIN Mode register (US_LINMR) is discarded. The response can contain 2 or 4 or 8 
data bytes.

Response Data Length

The last field of a frame is the checksum. The checksum contains the inverted 8- bit sum with carry, over all data
bytes or all data bytes and the protected identifier. Checksum calculation over the data bytes only is called classic
checksum and it is used for communication with LIN 1.3 slaves. Checksum calculation over the data bytes and the
protected identifier byte is called enhanced checksum and it is used for communication with LIN 2.0 slaves.

The USART can be configured to:

• Send/Check an Enhanced checksum automatically (CHKDIS = 0 & CHKTYP = 0)

• Send/Check a Classic checksum automatically (CHKDIS = 0 & CHKTYP = 1)

• Not send/check a checksum (CHKDIS = 1)

This configuration is made by the Checksum Type (CHKTYP) and Checksum Disable (CHKDIS) fields of the LIN
Mode register (US_LINMR).

If the checksum feature is disabled, the user can send it manually all the same, by considering the checksum as a
normal data byte and by adding 1 to the response data length (see 

).

Response Data Length if DLM = 1

0

0

2

0

1

2

1

0

4

1

1

8

User configuration: 1 - 256 data fields (DLC+1)

Identifier configuration: 2/4/8 data fields

Sync

Break

Sync

Field

Identifier

Field

Checksum

Field

Data

Field

Data

Field

Data

Field

Data

Field