Communication Processor Module
16-224
MPC823e REFERENCE MANUAL
MOTOROLA
COMMUNICATION
16
SCCs
CD—Carrier Detect Lost
This bit indicates that the carrier detect signal has been negated while the SCCx UART
controller was receiving a message.
DATA LENGTH
This field represents the number of octets that the communication processor module writes
into this buffer descriptor’s data buffer. It is written by the communication processor module
once the buffer descriptor is closed.
RX DATA BUFFER POINTER
This field always points to the first location of the associated data buffer, which can be even
or odd. The buffer can reside in internal or external memory.
16.9.15.17 SCCx UART TRANSMIT BUFFER DESCRIPTOR.
The communication
processor module receives data transmitted 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 and indicates error
conditions so that the processor knows that the buffers have been serviced.
Note:
The actual amount of memory allocated for this buffer must be at least as much
as the contents of the MRBLR.
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
OFFSET + 0
R
RES
W I CR A CM
P NS RESERVED CT
OFFSET + 2
DATA LENGTH
OFFSET + 4
TX DATA BUFFER POINTER
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.
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