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MC9S12XF512_1 Datasheet, PDF (557/1306 Pages) Freescale Semiconductor, Inc – S12X Microcontrollers | |||
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Chapter 13 FlexRay Communication Controller (FLEXRAY)
Table 13-90. Frame Data Write Access Constraints
Field
single buffered
double buffered
commit side
transmit side
DATA, MID, NMV POC:conï¬g or MB_DIS POC:conï¬g or MB_DIS POC:conï¬g or MB_DIS
or MB_LCK
or MB_LCK
Table 13-91. Frame Data Field Descriptions
Field
Description
DATA[0:N-1] Message Data â Provides the message data received or to be transmitted.
For receive message buffer and receive FIFOs, this ï¬eld provides the message data received for this message
buffer.
For transmit message buffers, the ï¬eld provides the message data to be transmitted.
MID[0:1]
Message Identiï¬er â If the payload preamble bit PPI is set in the message buffer frame header, the MID ï¬eld
holds the message ID of a dynamic frame located in the message buffer. The receive FIFO ï¬lter uses the
received message ID for message ID ï¬ltering.
NMV[0:11]
Network Management Vector â If the payload preamble bit PPI is set in the message buffer frame header, the
network management vector ï¬eld 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.
13.6.6 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 conï¬gured by the application. After the initial
conï¬guration, the message buffer can be reconï¬gured later. The set of the conï¬guration data for individual
message buffers is given in Section 13.6.3.4.1, âIndividual Message Buffer Conï¬guration Dataâ.
13.6.6.1 Individual Message Buffer Conï¬guration
The individual message buffer conï¬guration consists of two steps. The ï¬rst step is the allocation of the
required amount of memory for the FRM. The second step is the programming of the message buffer
conï¬guration registers, which is described in this section.
13.6.6.1.1 Common Conï¬guration Data
One part of the message buffer conï¬guration 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:conï¬g state.
The application conï¬gures the number of utilized individual message buffers by writing the message
buffer number of the last utilized message buffer into the LAST_MB_UTIL ï¬eld in the Message Buffer
Segment Size and Utilization Register (MBSSUTR).
MC9S12XF - Family Reference Manual, Rev.1.19
Freescale Semiconductor
557
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