FlexRay Communication Controller (FLEXRAY)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
30-80
Freescale Semiconductor
Preliminary
Each individual message buffer consists of two parts, the physical message buffer, which is located in the
FRM, and the message buffer control data, which are located in dedicated registers. The structure of an
individual message buffer is given in
Each individual message buffer has a message buffer number n assigned, which determines the set of
message buffer control registers associated to this individual message buffer. The individual message
buffer with message buffer number
n
is controlled by the registers MBCCSRn, MBCCFRn, MBFIDRn,
and MBIDXRn.
The connection between the message buffer control registers and the physical message buffer is
established by the message buffer index field MBIDX in the
Message Buffer Index Registers (MBIDXRn)
.
The start address SADR_MBHF of the related message buffer header field in the FRM is determined
according to
.
SADR_MBHF = (MBIDXRn[MBIDX] * 10) + SYS_MEM_BASE_ADDR
Eqn. 30-3
Figure 30-100. Individual Message Buffer Structure
30.6.3.1.1
Individual Message Buffer Segments
The set of the individual message buffers can be split up into two message buffer segments using the
Message Buffer Segment Size and Utilization Register (MBSSUTR)
. All individual message buffers with
a message buffer number n <= MBSSUTR.LAST_MB_SEG1 belong to the first message buffer segment.
All individual message buffers with a message buffer number n > MBSSUTR.LAST_MB_SEG1 belong
to the second message buffer segment. The following rules apply to the length of the message buffer data
field:
•
all physical message buffers associated to individual message buffers that belong to the same
message buffer segment must have message buffer data fields of the same length
•
the minimum length of the message buffer data field for individual message buffers in the first
message buffer segment is 2 * MBDSR.MBSEG1DS bytes
•
the minimum length of the message buffer data field for individual message buffers assigned to the
second segment is 2 * MBDSR.MBSEG2DS bytes.
MBFIDRn
Message Buffer Control Registers
MBCCSRn
MBCCFRn
MBIDXRn
(min) MBDSR[MBSEG1DS] * 2 bytes / MBDSR[MBSEG2DS] * 2 bytes
Data Field Offset
Frame Data
Message Buffer Header Field
Message Buffer Data Field
Slot Status
Frame Header
SADR_MBDF
SADR_MBHF
XBAR