Motorola MPC823e - Page 699

Communication Processor Module
MOTOROLA MPC823e REFERENCE MANUAL 16-245
COMMUNICATION
16
PROCESSOR MODULE
SCCs
Figure 16-80. SCC2 HDLC Receive Buffer Descriptor Example
MRBLR = 8 BYTES FOR SCC2
BUFFER
8 BYTES
TIME
BUFFER
8 BYTES
EMPTY
BUFFER
8 BYTES
EMPTY
BUFFER
FULL
E
LENGTH
RECEIVE BD 0
STATUS
0008
POINTER
0
E
LENGTH
RECEIVE BD 1
STATUS
000B
POINTER
0
1
0
L
E
LENGTH
RECEIVE BD 2
STATUS
0003
POINTER
0
AB
1
E
LENGTH
RECEIVE BD 3
STATUS
XXXX
POINTER
1
BUFFER
8 BYTES
PRESENT
TIME
EMPTY
BUFFER
STILL
EMPTY
ABORT WAS
RECEIVED
AFTER CONTROL
BYTE
BUFFER
CLOSED WHEN
CLOSING FLAG
RECEIVED
1
F
0
LF
1
1
STORED IN RX BUFFER
STORED IN RX BUFFER
FAACIIIII
ICRCRF
TWO FRAMES
RECEIVED IN HDLC
LINE IDLE
ADDRESS 1
ADDRESS 2
CONTROL BYTE
LAST I-FIELD BYTE
CRC BYTE 1
CRC BYTE 2
ADDRESS 1
ADDRESS 2
CONTROL BYTE
5
INFORMATION
(I-FIELD) BYTES
UNEXPECTED ABORT
OCCURS BEFORE
CLOSING FLAG
ABORT/IDLEFAAC
F = FLAG
A = ADDRESS BYTE
C = CONTROL BYTE
I = INFORMATION BYTE
LEGEND:
CR = CRC BYTE
L
F
32-BIT BUFFER POINTER
32-BIT BUFFER POINTER
32-BIT BUFFER POINTER
32-BIT BUFFER POINTER