Enhanced Serial Communication Interface (eSCI)
26-44
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
–
•
select transmission DMA stop on
bit error
detection
–
[BSTP]:= 1
•
enable both
transmitter
and
receiver
–
–
[RE]:= 1
26.4.6.2
LIN frame formats
The term LIN frame refers to a sequence of LIN byte fields preceded by a break character, both are
described in
. The eSCI module allows to generate LIN frames for LIN
slaves of LIN standards 1.3 and 2.0.
26.4.6.2.1
Standard LIN frames
A standard LIN frame, shown in
consists of a break character, a sync field, an ID field, zero
or more data fields, and a checksum field. The data fields and the checksum field are generated by the LIN
master for TX LIN frames and generated by the LIN slave for RX LIN frames. The header fields will
always be generated by the LIN master.
Figure 26-38. Standard LIN frame format
26.4.6.2.2
CRC Enhanced LIN frames
The CRC Enhanced LIN frames shown in
contain two additional CRC byte fields. These
fields are located between the last data field and the Checksum field. The value of the CRC is calculated
on the same byte fields as the Checksum is calculated on. The polynom used for the CRC calculation is
defined by
LIN CRC Polynomial Register (eSCI_LPR)
. The eSCI module generates the CRC fields for
TX frames and checks the CRC fields for RX frames if the CRC bit in the
was written with a value of 1.
Figure 26-39. CRC Enhanced LIN frame format
The CRC Enhanced LIN frames are not part of the LIN standard.
26.4.6.3
LIN TX Frame generation
The eSCI module supports two modes of LIN TX Frame generation, the CPU controlled mode and the
DMA controlled mode. In the CPU controlled mode, the application provides the required frame
configuration and frame data by subsequent CPU write accesses to the
. In the DMA controlled mode, the DMA controller provides the required frame configuration
and frame data in response to DMA requests generated by the eSCI module.
Break
Synch
Identifier
Data 1
Data 2
Data N
Checksum
Break
Synch
Identifier
Data 1
Data 2
Data N
Checksum
CRC1
CRC2
Summary of Contents for PXR4030
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