07-11-2012, 04:19 PM
LIN Protocol
LIN Protocol.pdf (Size: 387.8 KB / Downloads: 24)
Features of LIN
Single master with multiple slaves concept
Low cost silicon implementation based on common
UART/SCI interface hardware, an equivalent in software
Self synchronization without a quartz or ceramics
resonator in the slave nodes
Deterministic signal transmission with signal propagation
time computable in advance
Low cost single-wire implementation
Speed up to 20 kbps.
Signal based application interaction
Predictable behavior & re configurability
LIN Protocol
Master Task
Has control over the whole Bus and Protocol.
The master controls which message at what times is to be
transferred over the bus.
Slave Task
Is one of the 2-16 members on the bus and receives or
transmits data when appropriate ID is sent by the master
Slave waits for Sync Break
Slave synchronizes on Sync Byte
According to ID, slave determines what to do
A frame consists of a header (provided by the master task)
and a response (provided by a slave task).
The header consists of a break field and sync field followed
by a frame identifier. The frame identifier uniquely defines the
purpose of the frame. The slave task appointed for providing
the response associated with the frame identifier transmits it,
as depicted below. The response consists of a data field and
a checksum field.
Frame Structure: Check Sum
The checksum contains the inverted eight bit sum with carry over all
data bytes or all data bytes and the protected identifier.
Eight bit sum with carry is equivalent to sum all values and subtract 255
every time the sum is greater or equal to 256.
The receiving node can easily check the
consistency of the received frame by using
the same addition mechanism.
When the received checksum (0xE6) is
added to the intermediate result (0x19) the
sum shall be 0xFF.
Frame identifiers 60 (0x3C) to 61 (0x3D)
shall always use classic checksum