AN1278 datasheet(42/44 Pages) STMICROELECTRONICS

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LIN (LOCAL INTERCONNECT NETWORK) SOLUTIONS

4.4.3 Using the on-chip SCI

Using the on-chip SCI the flexibility is considerably increased. The CPU load is very low and

the capability of the application software to run at the same time as the LIN software is high.

Firstly a LIN interrupt occurs every byte instead of every bit (even every half bit in transmis-

sion) in the timer solution. And secondly the received byte is buffered in hardware which al-

lows a lot of flexibility.

Figure 23. CPU load with on-chip SCI peripheral

4.4.3.1 Reception

The on-chip peripheral is handling the SCI communication and notifies a reception at the end

of each byte. A LIN interrupt is then generated and handles the received data according to the

LIN protocol.

Figure 24. Reception Notification Interrupt

When the SCI notifies the reception it copies at the same time the received value into a buffer.

As a result the peripheral is ready for the next reception and the software can still hold the re-

ceived data until the end of the new reception. Afterwards an overrun condition occurs.

CPU not used for LIN

LIN interrupt running

LIN Bus

LIN frame

stop

bit

1 byte

SCI reception notification

LIN interrupt

AN1278 Datasheet(PDF) 42 Page - STMicroelectronics