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Communication Processor Module
0
1
2
E
RES
W
OFFSET + 0
OFFSET + 2
OFFSET + 4
OFFSET + 6
NOTE:
You are only responsible for initializing the items in bold.
E—Empty
0 = The data buffer associated with this RX buffer descriptor has been filled with data
or reception has been aborted because of an error condition. The core is free to
examine or write to any fields of this RX buffer descriptor. The communication
processor module does not use this buffer descriptor again as long as the E bit is
zero.
1 = The data buffer associated with this buffer descriptor is empty or is currently
receiving data. This RX buffer descriptor and its associated receive buffer are
owned by the communication processor module. Once the E bit is set, the core
must not write any fields of this RX buffer descriptor.
Bits 1, 9, and 13—Reserved
These bits are reserved and must be set to 0.
W—Wrap (Final Buffer Descriptor in Table)
0 = This is not the last buffer descriptor in the RX buffer descriptor table.
1 = This is the last buffer descriptor in the RX buffer descriptor table. After this buffer
has been used, the communication processor module receives incoming data into
the first buffer descriptor that RBASE points to in the table. The number of RX
buffer descriptors in this table are programmable and determined only by the W bit
and overall space constraints of the dual-port RAM.
I—Interrupt
0 = No interrupt is generated after this buffer is filled.
1 = The RX bit in the SCCE–UART register is set when this buffer is completely filled
by the communication processor module, indicating the need for the core to
process the buffer. The RX bit can cause an interrupt if it is enabled.
C—Control Character
0 = This buffer does not contain a control character.
1 = This buffer contains a control character. The last byte in the buffer is one of the
user-defined control characters.
16-222
3
4
5
6
7
I
C
A
CM
ID
DATA LENGTH
RX DATA BUFFER POINTER
MPC823e REFERENCE MANUAL
8
9
10
11
12
AM
RES
BR
FR
PR
13
14
15
RES
OV
CD
MOTOROLA
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