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FlexRay Module (FLEXRAYV2)
MFR4300 Data Sheet, Rev. 1
142
Freescale Semiconductor
3.4.4.3
Sync Frame Table Area
The sync frame table area is used to provide a copy of the internal sync frame tables for application access.
Refer to
Section 3.4.12, “Sync Frame ID and Sync Frame Deviation Tables
” for the description of the sync
frame table area.
3.4.5
Physical Message Buffer Description
This section provides a detailed description of the usage and the content of the two parts of a physical
message buffer, the message buffer header field and the message buffer data field.
3.4.5.1
Message Buffer Protection and Data Consistency
The physical message buffers are located in the FRM. The FlexRay module provides no means to protect
the FRM from uncontrolled or illegal host or other client write access. To ensure data consistency of the
physical message buffers, the application must follow the write access scheme that is given in the
description of each of the physical message buffer fields.
3.4.5.2
Message Buffer Header Field Description
This section provides a detailed description of the usage and content of the message buffer header field. A
description of the structure of the message buffer header fields is given in
Section 3.4.2.1, “Message Buffer
Header Field
”. Each message buffer header field consists of three sections: the frame header section, the
data field offset, and the slot status section. For a detailed description of the Data Field Offset, see
Section 3.4.2.1.2, “Data Field Offset
”.
3.4.5.2.1
Frame Header Section Description
Frame Header Section Content
The semantic and content of the frame header section depends on the message buffer type.
For individual receive message buffers and receive FIFOs, the frame header receives the frame header data
of the
first valid frame
received on the assigned channels. If a receive message buffer is assigned to both
channels, the first valid frame received on either channel A or channel B is stored.
For receive shadow buffers, the frame header receives the frame header data of the current frame received
regardless of whether the frame is valid or not.
For single and double transmit message buffers, the application writes the frame header of the frame to be
transmitted into this location. The frame header will be read out when the frame is transferred to the
FlexRay bus.
The structure of the frame header in the message buffer header field is given in
Figure 3-102
. A detailed
description of the frame header fields is given in
Table 3-81
.