Infineon TLE984 QX Series, User Manual

Page: 632 / 972

User Manual 632 Rev. 1.1
2019-03-18
TLE984xQX
Microcontroller with LIN and Power Switches for Automotive Applications
UART1/UART2
13 bits of dominant value, including the start bit, followed by a sync break delimiter, as shown in Figure 168 .
The sync break delimiter will be at least one nominal bit time long.
A slave node will use a sync break detection threshold of 11 nominal bit times.
Figure 168 The Sync Break Field
The sync byte is a specific pattern for the determination of the time base. The sync byte field consists of the
data value 55
H
, as shown in Figure 169 .
A slave task is always able to detect the sync break/sync sequence, even if it expects a byte field (assuming the
byte fields are separated from each other). If this happens, detection of the sync break/sync sequence will
abort the transfer in progress and processing of the new frame will commence.
Figure 169 The Sync Byte Field
The slave task will receive and transmit data when an appropriate ID is sent by the master:
1. The slave waits for the sync break
2. The slave synchronizes on the sync byte
3. The slave snoops for the ID
4. According to the ID, the slave determines whether to receive or transmit data, or do nothing
5. When transmitting, the slave sends 2, 4 or 8 data bytes, followed by a Check Byte
19.7.2 LIN Header Transmission
LIN header transmission is only applicable in Master Mode. In the LIN communication, a master task decides
when and which frame is to be transferred on the bus. It also identifies a slave task to provide the data
transported by each frame. The information needed for the handshaking between the master and slave, tasks
is provided by the master task through the header part of the frame.
The header consists of a sync break and sync byte pattern followed by an identifier. Among these three fields,
only the sync break pattern cannot be transmitted as a normal 8-bit UART data. The sync break must contain
a dominant value of 13 bits or more to ensure proper synchronization of slave nodes.
In the LIN communication, a slave task is required to be synchronized at the beginning of the protected
identifier field of the frame. For this purpose, every frame starts with a sequence consisting of a sync break
followed by a sync byte field. This sequence is unique and provides enough information for any slave task to
detect the beginning of a new frame and to be synchronized at the start of the identifier field.
Start
Bit
Break
delimit
Start
Bit
Stop
Bit