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FlexRay Communication Controller (FlexRay)
MPC5644A Microcontroller Reference Manual, Rev. 6
1532
Freescale Semiconductor
physical message buffers are located in the FlexRay memory area.The structure of a physical message
buffer is depicted in
.
A physical message buffer consists of two fields, the
message buffer header field
and the
message buffer
data field
. The message buffer header field contains the
frame header
, the
data field offset
, and the
slot
status
.The message buffer data field contains the
frame data
.
The connection between the two fields is established by the
data field offset
.
Figure 33-113. Physical message buffer structure
33.6.2.1
Message buffer header field
The message buffer header field is a contiguous region in the FlexRay memory area and occupies ten bytes.
It contains the frame header, the data field offset, and the slot status. Its structure is shown in
SADR_MBHF
of the message buffer header field must be 16-bit
aligned.
33.6.2.1.1
Frame header
The frame header occupies the first six bytes in the message buffer header field. It contains all FlexRay
frame header related information according to the
FlexRay Communications System Protocol
Specification, Version 2.1 Rev A
. A detailed description of the usage and the content of the frame header
Section 33.6.5.2.1, Frame header description”
.
33.6.2.1.2
Data field offset
The data field offset follows the frame header in the message buffer data field and occupies two bytes. It
contains the offset of the corresponding message buffer data field with respect to the CC FlexRay memory
area base address as provided by SMBA field in the
System Memory Base Address Register
”. The data field offset is used to determine the start address
SADR_MBDF
of the
corresponding message buffer data field in the FlexRay memory area according to
SADR_MBDF = [Data Field Offset] + SMBA
Eqn. 33-1
33.6.2.1.3
Slot status
The slot status occupies the last two bytes of the message buffer header field. It provides the slot and frame
status related information according to the
FlexRay Communications System Protocol Specification,
Data Field Offset
Frame Data
Message Buffer Header Field
Message Buffer Data Field
Slot Status
Frame Header
SADR_MBDF
SADR_MBHF
FlexRay
Memory
Summary of Contents for MPC5644A
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Page 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
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Page 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Page 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Page 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
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