Motorola MPC823e Reference Manual page 766

Communication Processor Module
CR—CRC Error indication bits
This bit indicates that this frame contains a CRC error. The received CRC bytes are always
written to the receive buffer.
OV—Overrun
This bit indicates that a receiver overrun has occurred during buffer reception.
CD—Carrier Detect Lost
This bit indicates that the CDx pin is negated during buffer reception.
DATA LENGTH
This field represents the number of octets that the communication processor module writes
into this buffer descriptor data buffer. The communication processor module only writes it
once as the buffer is closed. The actual amount of memory allocated for this buffer must be
greater than or equal to MRBLR.
RX DATA BUFFER POINTER
This field always points to the first location of the associated data buffer and must be
divisible by four, unless the RFW bit in the GSMR_H is set to 8 bits wide, even or odd. The
buffer can reside in internal or external memory.
16.9.21.10 SCCx TRANSPARENT TRANSMIT BUFFER DESCRIPTOR. Data is sent to
the communication processor module for transmission on an SCCx channel by arranging it
in buffers referenced by the channel's transmit (TX) buffer descriptor table. Using the buffer
descriptors, the communication processor module confirms transmission or indicates error
conditions so that the processor knows the buffers have been serviced. You must prepare
the status and control bits before transmission, but they are set by the communication
processor module after the buffer has been transmitted.
0 1 2
R RES W
OFFSET + 0
OFFSET + 2
OFFSET + 4
OFFSET + 6
NOTE: You are only responsible for initializing the items in bold.
Note: The communication processor module sets all the status bits in this buffer
descriptor, but you must clear them before submitting the buffer descriptor to the
communication processor module.
16-312
3 4 5 6 7
I L TC CM
DATA LENGTH
TX DATA BUFFER POINTER
MPC823e REFERENCE MANUAL
8 9 10 11 12
RESERVED
13 14 15
UN CT
MOTOROLA