Two bus states — Sleep-mode and active — are used within the LIN protocol. While data is on the bus, all LIN-nodes are requested to be in active state. After a specified timeout, the nodes enter Sleep mode and will be released back to active state by a WAKEUP frame. This frame may be sent by any node requesting activity on the bus, either the LIN Master following its internal schedule, or one of the attached LIN Slaves being activated by its internal software application. After all nodes are awakened, the Master continues to schedule the next Identifier. [12][13]
6. Schedule table
One of key properties of LIN protocol is Schedule Tables. It’s applied for managing the timing of frame slots and traffic control on the bus. The application of Schedule Tables in LIN protocol guarantees that LIN bus won’t be overloaded.
For a specifically implemented LIN system, it’s a constant. It’s used to calculate the time length of a frame slot according to the formula Tframe_slot = Tbase * n, in which n is different for each frame slot. It depends on the length of a frame slot.
A schedule table can incorporate more than one frame slot as shown in “Figure 29”. If only one schedule table is present in a system. When it reaches the end of the schedule table, the schedule will go back to the start of the schedule table and continue performing along the sequence in the schedule table.