NXP Semiconductors MPC5644A, Reference Manual, Page: 1542 / 1735

FlexRay Communication Controller (FlexRay)
MPC5644A Microcontroller Reference Manual, Rev. 6
1542 Freescale Semiconductor
33.6.5.2 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 33.6.2.1, 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 33.6.2.1.2, Data field offset ”.
33.6.5.2.1 Frame header description
Frame header 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.
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 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 for receive message buffers and the
receive FIFO is given in
Figure 33-119 . A detailed description is given in Table 33-95 .
Figure 33-119. Frame header structure (receive message buffer and receive FIFO)
The structure of the frame header in the message buffer header field for transmit message buffers is given
in
Figure 33-120 . A detailed description is given in Table 33-96 . The checks that will be performed are
described in Frame header checks .
Figure 33-120. Frame header structure (transmit message buffer)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
0x0 R PPI NUF SYF SUF FID
0x2 0 0 CYCCNT 0 PLDLEN
0x4 0 0 0 0 0 HDCRC
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
0x0 R PPI NUF SYF SUF FID
0x2 CYCCNT PLDLEN
0x4 HDCRC
= not used
= checked = checked if static slot