Datasheet

611
32117D–AVR-01/12
AT32UC3C
25.6.9.12 Checksum
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 (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 Section
25.6.9.11).