FlexRay Communication Controller (FLEXRAY)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
30-96
Freescale Semiconductor
Preliminary
The application configures the size of the two segments of individual message buffers by writing the
message buffer number of the last message buffer in the first segment into the LAST_MB_SEG1 field in
the
Message Buffer Segment Size and Utilization Register (MBSSUTR)
The application configures the length of the message buffer data fields for both of the message buffer
segments by writing to the MBSEG2DS and MBSEG1DS fields in the
Message Buffer Data Size Register
Depending on the current receive functionality of the FlexRay block, the application must configure the
receive shadow buffers. For each segment and for each channel with at least one individual receive
message buffer assigned, the application must configure the related receive shadow buffer using the
Receive Shadow Buffer Index Register (RSBIR)
30.6.6.1.2
Specific Configuration Data
The second part of the message buffer configuration data is specific for each message buffer.
These data can be changed only when either
•
the protocol is in the
POC:config
state or
•
the message buffer is disabled, i.e. MBCCSRn.EDS = 0
The individual message buffer type is defined by the MTD and MBT bits in the
Configuration, Control, Status Registers (MBCCSRn)
The message buffer specific configuration data are
1. MCM, MBT, MTD bits in
Message Buffer Configuration, Control, Status Registers (MBCCSRn)
Message Buffer Cycle Counter Filter Registers (MBCCFRn)
Message Buffer Frame ID Registers (MBFIDRn)
Message Buffer Index Registers (MBIDXRn)
The meaning of the specific configuration data depends on the message buffer type, as given in the detailed
message buffer type descriptions
Section 30.6.6.2, “Single Transmit Message Buffers
Section 30.6.6.4, “Double Transmit Message Buffer
”.
30.6.6.2
Single Transmit Message Buffers
The section provides a detailed description of the functionality of single buffered transmit message buffers.
A single transmit message buffer is used by the application to provide message data to the FlexRay block
that will be transmitted over the FlexRay Bus. The FlexRay block uses the transmit message buffers to
Table 30-91. Individual Message Buffer Types
MBCCSRn.MTD
MBCCSRn.MBT
Individual Message Buffer Description
0
0
Receive Message Buffer
0
1
Reserved
1
0
Single Transmit Message Buffer
1
1
Double Transmit Message Buffer