Freescale Semiconductor FlexRay MFR4310, Reference Manual

Page: 152 / 268

FlexRay Module (FLEXRAYV4)
MFR4310 Reference Manual, Rev. 2
152 Freescale Semiconductor
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
(MBDSR) .
Depending on the current receive functionality of the FlexRay module, 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) .
3.4.6.1.2 Specific Configuration Data
The second part of the message buffer configuration data is specific for each message buffer.
This data can be changed only when either of the following two events occur:
• The protocol is in the POC:config state
• The message buffer is disabled, MBCCSRn.EDS equals 0
The individual message buffer type is defined by the MTD and MBT bits in the Message Buffer
Configuration, Control, Status Registers (MBCCSRn) as given in Table 3-89 .
The message buffer specific configuration data are
1. MCM, MBT, MTD bits in Message Buffer Configuration, Control, Status Registers (MBCCSRn)
2. all fields and bits in Message Buffer Cycle Counter Filter Registers (MBCCFRn)
3. all fields and bits in Message Buffer Frame ID Registers (MBFIDRn)
4. all fields and bits in 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 3.4.6.2, “Single Transmit Message Buffers ”, Section 3.4.6.3,
“Receive Message Buffers ”, and Section 3.4.6.4, “Double Transmit Message Buffer ”.
3.4.6.2 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 module
transmitted over the FlexRay Bus. The FlexRay module uses the transmit message buffers to provide
Table 3-89. 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