NXP Semiconductors MPC5644A, Reference Manual, Page: 1531 / 1735

FlexRay Communication Controller (FlexRay)
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor 1531
33.5.2.81 Message Buffer Index Registers (FR_MBIDXRn)
33.6 Functional description
This section provides a detailed description of the functionality implemented in the CC.
33.6.1 Message buffer concept
The CC uses a data structure called message buffer to store frame data, configuration, control, and status
data. Each message buffer consists of two parts, the message buffer control data and the physical message
buffer. The message buffer control data are located in dedicated registers. The structure of the message
buffer control data depends on the message buffer type and is described in Section 33.6.3, Message buffer
types ”. The physical message buffer is located in the FlexRay memory area and is described in
Section 33.6.2, Physical message buffer ”.
33.6.2 Physical message buffer
All FlexRay messages and related frame and slot status information of received frames and of frames to
be transmitted to the FlexRay bus are stored in data structures called
physical message buffers . The
Table 33-92. FR_MBFIDRn field description
Field Description
FID Frame ID — The semantic of this field depends on the message buffer transfer type.
• Receive Message Buffer: This field is used as a filter value to determine if the message buffer is
used for reception of a message received in a slot with the slot ID equal to FID.
• Transmit Message Buffer: This field is used to determine the slot in which the message in this
message buffer should be transmitted.
Base + 0x0106 (FR_MBIDXR0)
Base + 0x010E (FR_MBIDXR1)
...
Base + 0x04FE (FR_MBIDXR127) 16-bit write access required Write: POC:config or MB_DIS
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
R 0 0 0 0 0 0 0 0
MBIDX
W
Reset 0 0 0 0 0 0 0 0 – – – – – – – –
Figure 33-112. Message Buffer Index Registers (FR_MBIDXRn)
Table 33-93. FR_MBIDXRn field description
Field Description
MBIDX Message Buffer Index — This field provides the index of the message buffer header field of the
physical message buffer that is currently associated with this message buffer.
The application writes the index of the initially associated message buffer header field into this register.
The CC updates this register after frame reception or transmission.