User Manual
631
Rev. 1.1
2019-03-18
TLE984xQX
Microcontroller with LIN and Power Switches for Automotive Applications
UART1/UART2
19.7
LIN Support in UART
The UART module can be used to support the Local Interconnect Network (LIN) protocol for both master and
slave operations. The LIN baud rate detection feature, which consists of the hardware logic for break and sync
byte detection, provides the capability to detect the baud rate within LIN protocol using Timer 2 / Timer 21.
This allows the UART module to be synchronized to the LIN baud rate for data transmission and reception.
19.7.1
LIN Protocol
LIN is a holistic communication concept for local interconnected networks in vehicles. The communication is
based on the SCI (UART) data format, a single-master/multiple-slave concept, a clock synchronization for
nodes without stabilized time base. An attractive feature of LIN is the self-synchronization of the slave nodes
without a crystal or ceramic resonator, which significantly reduces the cost of hardware platform. Hence, the
baud rate must be calculated and returned with every message frame.
The structure of a LIN frame is shown in
. The frame consists of the:
• header, which comprises a sync break (13-bit time low), sync byte (55
H
), and ID field
• response time
• data bytes (according to UART protocol)
• checksum
Figure 166 The Structure of LIN Frame
Each byte field is transmitted as a serial byte, as shown in
. The LSB of the data is sent first and the
MSB is sent last. The start bit is encoded as a bit with value zero (dominant) and the stop bit is encoded as a
bit with value one (recessive).
Figure 167 The Structure of Byte Field
The sync break is used to signal the beginning of a new frame. It is the only field that does not comply with
. A sync break is always generated by the master task (in the Master Mode) and it must be at least
Frame slot
Frame
Response
Inter-
frame
space
Response
space
Header
Break
Sync
Protected
identifier
Data 1
Data 2
Data N
Checksum
LSB
(bit 0)
Start
Bit
Stop
Bit
MSB
(bit 7)
Byte field