Chapter 13 FlexRay Communication Controller (FLEXRAY)
MC9S12XF - Family Reference Manual, Rev.1.19
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Freescale Semiconductor
13.6.4.3
Sync Frame Table Area
The sync frame table area is used to provide a copy of the internal sync frame tables for application access.
sync frame table area.
13.6.5
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 eld and the message buffer data eld.
13.6.5.1
Message Buffer Protection and Data Consistency
The physical message buffers are located in the FRM. The FlexRay block 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 elds.
13.6.5.2
Message Buffer Header Field Description
This section provides a detailed description of the usage and content of the message buffer header eld. A
Buffer Header Field”. Each message buffer header eld consists of three sections: the frame header
section, the data eld offset, and the slot status section. For a detailed description of the Data Field Offset,
13.6.5.2.1
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 rst valid frame received on the assigned channels. If a receive message buffer is assigned to both
channels, the rst 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 eld is given in
Figure 13-105. A detailed
description of the frame header elds is given in
Table 13-84.