NXP Semiconductors MPC5644A, Reference Manual, Page: 1562 / 1735

FlexRay Communication Controller (FlexRay)
MPC5644A Microcontroller Reference Manual, Rev. 6
1562 Freescale Semiconductor
A receive message buffer is used to receive a message from the FlexRay Bus based on individual filter
criteria. The CC uses the receive message buffer to provide the following data to the application
1. message data received
2. information about the reception process
3. status information about the slot in which the message was received
A individual message buffer with message buffer number n is configured as a receive message buffer by
the following configuration settings
• FR_MBCCSRn[MBT] = 0 (single buffered message buffer)
• FR_MBCCSRn[MTD] = 0 (receive message buffer)
To certain message buffer fields, both the application and the CC have access. To ensure data consistency,
a message buffer locking scheme is implemented that is used to control the access to the data, control, and
status bits of a message buffer. The access regions for receive message buffers are depicted in
Figure 33-137 . A description of the regions is given in Table 33-110 . If an region is active as indicated in
Table 33-111 , the access scheme given for that region applies to the message buffer.
Figure 33-137. Receive message buffer access regions
Table 33-110. Receive message buffer access region description
Region
Access from
Region used for
Application Module
CFG read/write — Message Buffer Configuration, Message Data and Status Access
MSG read/write — Message Data, Header, and Status Access
RX — write-only Message Reception and Status Update
SR — read-only Message Buffer Search Data
Message Buffer Data Field: DATA[0-N]
Message Buffer Header Field: Frame Header
FR_MBCCSRn[DVAL/DUP]
Message Buffer Header Field: Slot Status
Message Buffer Header Field: Data Field Offset
FR_MBCCFRn[CHA/CHB/CCF*]
FR_MBFIDRn[FID]
FR_MBIDXRn[MBIDX]
FR_MBCCSRn[MTD]
RX
SR
CFG
MSG