NXP Semiconductors MPC5644A, Reference Manual, Page: 1533 / 1735

FlexRay Communication Controller (FlexRay)
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor 1533
Version 2.1 Rev A . A detailed description of the content and usage of the slot status is provided in
Section 33.6.5.2.3, Slot status description” .
33.6.2.2 Message buffer data field
The message buffer data field is a contiguous area of 2-byte entities. This field contains the frame payload
data, or a part of it, of the frame to be transmitted to or received from the FlexRay bus. The minimum
length of this field depends on the specific message buffer configuration and is specified in the message
buffer descriptions given in
Section 33.6.3, Message buffer types ”.
33.6.3 Message buffer types
The CC provides three different types of message buffers.
• Individual Message Buffers
• Receive Shadow Buffers
• Receive FIFO Buffers
For each message buffer type the structure of the physical message buffer is identical. The message buffer
types differ only in the structure and content of message buffer control data, which control the related
physical message buffer. The message buffer control data are described in the following sections.
33.6.3.1 Individual message buffers
The individual message buffers are used for all types of frame transmission and for dedicated frame
reception based on individual filter settings for each message buffer. The CC supports three types of
individual message buffers, which are described in
Section 33.6.6, Individual message buffer functional
description ”.
Each individual message buffer consists of two parts, the physical message buffer, which is located in the
FlexRay memory area, and the message buffer control data, which are located in dedicated registers. The
structure of an individual message buffer is given in
Figure 33-114 .
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 FR_MBCCSRn, FR_MBCCFRn,
FR_MBFIDRn, and FR_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
(FR_MBIDXRn) . The start address SADR_MBHF of the related message buffer header field in the
FlexRay memory area is determined according to Equation 33-2 .
SADR_MBHF = (FR_MBIDXRn[MBIDX] * 10) + SMBA Eqn. 33-2