
Message Buffer
MFR4200 Data Sheet, Rev. 0
Freescale Semiconductor
143
Where:
The size of the data field in the MFR4200 is limited to 32 bytes.
3.3.2
Message Buffer Field Descriptions
3.3.2.1
ID[10:0] — Frame ID Field
Each transmit and receive message buffer and the FIFO buffer contains a frame ID field. This field is
interpreted differently for receive message buffers, transmit message buffers, and the receive FIFO.
RO_NO/WR_CS
Host read access; host write access during the configuration state only
TX_CS_NO
Host read access; host write access:
– during the configuration state for all transmit message buffers
– during normal mode of operation for buffers configured for the dynamic segment of the
communication cycle (read-only access for static segment buffers)
RO
Host read-only access
WR
Host read/write access
NU
Reserved or read-only bits not used by the CC during operation
Table 3-14. Mapping between Buffer Layout and Active Receive/Transmit/FIFO Message Buffers
Message Buffer Layout
Active FIFO/Receive/Transmit
Message Buffers Register
R
*
P
P
N
FI
SYN
C
STAR
T UP
Frame ID (11 bits)
Active FIFO/Receive/Transmit Buffer Frame ID Register
R
Cycle Count (6 bits)
R
PayloadLength (7
bits)
Active FIFO/Receive/Transmit Buffer Cycle Counter and Payload
Length Register
R
Header CRC (11 bits)
Active FIFO/Receive/Transmit Buffer Header CRC Register
Message
ID1/Data1/NMVector1
Message
ID0/Data0/NMVector0
Active FIFO/Receive/Transmit Buffer Data 0 Register
Data3/NMVector3
Data2/NMVector2
Active FIFO/Receive/Transmit Buffer Data 1 Register
Data5/NMVector5
Data4/NMVector4
Active FIFO/Receive/Transmit Buffer Data 2 Register
Data7/NMVector7
Data6/NMVector6
Active FIFO/Receive/Transmit Buffer Data 3 Register
Data9/NMVector9
Data8/NMVector8
Active FIFO/Receive/Transmit Buffer Data 4 Register
Data11/NMVector11
Data10/NMVector10
Active FIFO/Receive/Transmit Buffer Data 5 Register
Data13
Data12
Active FIFO/Receive/Transmit Buffer Data 6 Register
…
…
…
Data31
Data30
Active FIFO/Receive/Transmit Buffer Data 15 Register
Message Buffer Slot Status Vector
Active FIFO/Receive/Transmit Buffer Message Buffer Slot Status
Vector Register