Datasheet

21.3.4. Schedule table
The master task (in the master node) transmits frame headers based on a schedule table. The schedule
table specifies the identifiers for each header and the interval between the start of a frame and the start of
the following frame. The master application may use different schedule tables and select among them.
21.3.5. Compatibility with LIN 1.3
LIN 2.1 is a super-set of LIN 1.3.
A LIN 2.1 master node can handle clusters consisting of both LIN 1.3 slaves and/or LIN 2.1 slaves. The
master will then avoid requesting the new LIN 2.1 features from a LIN 1.3 slave:
• Enhanced checksum
• Re-configuration and diagnostics
• Automatic baud rate detection
• “Response error” status monitoring
LIN 2.1 slave nodes can not operate with a LIN 1.3 master node (for example the LIN1.3 master does not
support the enhanced checksum).
The LIN 2.1 physical layer is backwards compatible with the LIN1.3 physical layer. But not the other way
around. The LIN 2.1 physical layer sets greater requirements, that is, a master node using the LIN 2.1
physical layer can operate in a LIN 1.3 cluster.
21.4. LIN / UART controller
The LIN/UART controller is divided in three main functions:
• Tx LIN Header function
• Rx LIN Header function
• LIN Response function
These functions mainly use two services:
• Rx service
• Tx service
Because these two services are basically UART services, the controller is also able to switch into an
UART function.
21.4.1. LIN overview
The LIN/UART controller is designed to match as closely as possible to the LIN software application
structure. The LIN software application is developed as independent tasks, several slave tasks and one
master task (c.f. Schedule table). The Atmel ATmega16M1/32M1/64M1 conforms to this perspective. The
only link between the master task and the slave task will be at the cross-over point where the interrupt
routine is called once a new identifier is available. Thus, in a master node, housing both master and slave
task, the Tx LIN Header function will alert the slave task of an identifier presence. In the same way, in a
slave node, the Rx LIN Header function will alert the slave task of an identifier presence.
When the slave task is warned of an identifier presence, it has first to analyze it to know what to do with
the response. Hardware flags identify the presence of one of the specific identifiers from 60 (0x3C) up to
63 (0x3F).
For LIN communication, only four interrupts need to be managed:
• LIDOK: New LIN identifier available
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