FlexRay Module (FLEXRAYV4)
MFR4310 Reference Manual, Rev. 2
Freescale Semiconductor 153
information about the transmission process and status information about the slot in which message was
transmitted.
The individual message buffer with message buffer number n is configured to be a single transmit message
buffer by the following settings:
• MBCCSRn.MBT equals 0 (single buffered message buffer)
• MBCCSRn.MTD equals 1 (transmit message buffer)
3.4.6.2.1 Access Regions
To certain message buffer fields, both the application and the FlexRay module have access. To ensure data
consistency, a message buffer locking scheme is implemented, which is used to control the access to the
data, control, and status bits of a message buffer. The access regions for single transmit message buffers
are depicted in Figure 3-109. A description of the regions is given in Table 3-90. If an region is active as
indicated in Table 3-91, the access scheme given for that region applies to the message buffer.
Figure 3-109. Single Transmit Message Buffer Access Regions
The trigger bits MBCCSRn.EDT and MBCCSRn.LCKT, and the interrupt enable bit MBCCSRn.MBIE
are not under access control and can be accessed from the application at any time. The status bits
Table 3-90. Single Transmit Message Buffer Access Regions Description
Region
Access from
Region used for
Application Module
CFG read/write - Message Buffer Configuration
MSG read/write - Message Data and Slot Status Access
NF - read-only Message Header Access for Null Frame Transmission
TX - read/write Message Transmission and Slot Status Update
CM - read-only Message Buffer Validation
SR - read-only Message Buffer Search
Message Buffer Data Field: DATA[0-N]
Message Buffer Header Field: Frame Header
MBCCSRn.CMT
Message Buffer Header Field: Slot Status
Message Buffer Header Field: Data Field Offset
MBCCFRn.MTM/CHA/CHB/CCF*
MBFIDRn.FID
MBIDXRn.MBIDX
MBCCSRn.MBT/MTD
TX
NF
CMT
SR
CFG
MSG
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