FlexRay Communication Controller (FLEXRAY)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
Freescale Semiconductor
30-95
Preliminary
30.6.6
Individual Message Buffer Functional Description
The FlexRay block provides three basic types of individual message buffers:
1. Single Transmit Message Buffers
2. Double Transmit Message Buffers
3. Receive Message Buffers
Before an individual message buffer can be used, it must be configured by the application. After the initial
configuration, the message buffer can be reconfigured later. The set of the configuration data for individual
message buffers is given in
Section 30.6.3.4.1, “Individual Message Buffer Configuration Data
30.6.6.1
Individual Message Buffer Configuration
The individual message buffer configuration consists of two steps. The first step is the allocation of the
required amount of memory for the FRM. The second step is the programming of the message buffer
configuration registers, which is described in this section.
30.6.6.1.1
Common Configuration Data
One part of the message buffer configuration data is common to all individual message buffers and the
receive shadow buffers. These data can only be set when the protocol is in the
POC:config
state.
The application configures the number of utilized individual message buffers by writing the message
buffer number of the last utilized message buffer into the LAST_MB_UTIL field in the
Segment Size and Utilization Register (MBSSUTR)
.
Table 30-89. Frame Data Write Access Constraints
Field
single buffered
double buffered
commit side
transmit side
DATA, MID, NMV
POC:config
or MB_DIS
or MB_LCK
POC:config
or MB_DIS
or MB_LCK
POC:config
or MB_DIS
Table 30-90. Frame Data Field Descriptions
Field
Description
DATA[0:N-1] Message Data — Provides the message data received or to be transmitted.
For receive message buffer and receive FIFOs, this field provides the message data received for this message
buffer.
For transmit message buffers, the field provides the message data to be transmitted.
MID[0:1]
Message Identifier — If the payload preamble bit PPI is set in the message buffer frame header, the MID field
holds the message ID of a dynamic frame located in the message buffer. The receive FIFO filter uses the received
message ID for message ID filtering.
NMV[0:11]
Network Management Vector — If the payload preamble bit PPI is set in the message buffer frame header, the
network management vector field holds the network management vector of a static frame located in the message
buffer.
Note: The MID and NMV bytes replace the corresponding DATA bytes.
