FlexRay Communication Controller (FLEXRAY)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
Freescale Semiconductor
30-105
Preliminary
Message Buffer Status Update after Null Frame Transmission
After the transmission of a null frame, the status of the message buffer that was used for the null frame
transmission is not changed at all. The slot status field is not updated, the status and control flags are not
changed, and the interrupt flag is not set.
30.6.6.3
Receive Message Buffers
The section provides a detailed description of the functionality of the receive message buffers.
A receive message buffer is used to receive a message from the FlexRay Bus based on individual filter
criteria. The FlexRay block 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
•
MBCCSRn.MBT = 0 (single buffered message buffer)
•
MBCCSRn.MTD = 0 (receive message buffer)
To certain message buffer fields, both the application and the FlexRay block 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
. A description of the regions is given in
. If an region is active as indicated in
, the access scheme given for that region applies to the message buffer.
Figure 30-120. Receive Message Buffer Access Regions
Message Buffer Data Field: DATA[0-N]
Message Buffer Header Field: Frame Header
MBCCSRn.DVAL/DUP
Message Buffer Header Field: Slot Status
Message Buffer Header Field: Data Field Offset
MBCCFRn.CHA/CHB/CCF*
MBFIDRn.FID
MBIDXRn.MBIDX
MBCCSRn.MTD
RX
SR
CFG
MSG