Data Sheet
April 1997
T7121 HDLC Interface for ISDN (HIFI-64)
Functional Description (continued)
TLBIT = 1
(R13) TRANSMITTER BIT MASK
TBM7 TBM0
(TRANSMIT LSB FIRST)
DIRECTION OF TRANSMISSION
FIRST BIT
TIME-SLOT DATA
TRANSMITTED
0 0 0 0 0 0 1 1
MSB
BIT 7
LSB
BIT 0
G
E
H
F
3 3 3 3 3 3 * G H
1ST TIME SLOT
2ND TIME SLOT
a b c d e f g h
TRANSMIT FIFO
3 3 3 3 3 3 E F
3 3 3 3 3 3 C D
3 3 3 3 3 3 A B
HDLC
3RD TIME SLOT
4TH TIME SLOT
C
A
D
B
TRANSMITTER HDLC
PROCESSES LSB FIRST
*3 = 3-STATE.
RLBIT = 1
(RECEIVE LSB FIRST)
(R12) RECEIVER BIT MASK
FIRST BIT RECEIVED
RBM7
RBM0
TIME-SLOT DATA
H G X X X X X X*
0 0 0 0 0 0 1 1
MSB
BIT 7
LSB
BIT 0
H
F
G
E
1ST TIME SLOT
2ND TIME SLOT
a b c d e f g h
RECEIVE FIFO
F E X X X X X X
D C X X X X X X
B A X X X X X X
HDLC
3RD TIME SLOT
4TH TIME SLOT
D
B
C
A
RECEIVER HDLC
EXPECTS LSB FIRST
*X = DON'T CARE. THESE BITS
ARE IGNORED BY THE RECEIVER.
DIRECTION OF RECEPTION
TLBIT = 0
(TRANSMIT MSB FIRST)
(R13) TRANSMITTER BIT MASK
TBM7 TBM0
DIRECTION OF TRANSMISSION
FIRST BIT
TIME-SLOT DATA
H G 3 3 3 3 3 3*
0 0 0 0 0 0 1 1
TRANSMITTED
1ST TIME SLOT
2ND TIME SLOT
MSB
BIT 7
LSB
BIT 0
G
E
H
F
a b c d e f g h
TRANSMIT FIFO
F E 3 3 3 3 3 3
D C 3 3 3 3 3 3
B A 3 3 3 3 3 3
HDLC
3RD TIME SLOT
4TH TIME SLOT
C
A
D
B
TRANSMITTER HDLC
PROCESSES LSB FIRST
*3 = 3-STATE.
RLBIT = 0
(RECEIVE MSB FIRST)
(R12) RECEIVER BIT MASK
FIRST BIT RECEIVED
RBM7
RBM0
TIME-SLOT DATA
X*X X X X X G H
0 0 0 0 0 0 1 1
MSB
BIT 7
LSB
BIT 0
H
F
G
E
1ST TIME SLOT
2ND TIME SLOT
a b c d e f g h
RECEIVE FIFO
X X X X X X E F
X X X X X X C D
X X X X X X A B
HDLC
3RD TIME SLOT
4TH TIME SLOT
D
B
C
A
RECEIVER HDLC
EXPECTS LSB FIRST
*X = DON'T CARE. THESE BITS
ARE IGNORED BY THE RECEIVER.
DIRECTION OF RECEPTION
Note: abcdefgh are not the same as ABCDEFGH due to HDLC processing.
5-5034
Figure 8. 16 kbits/s Operation
Lucent Technologies Inc.
17
AGERE [ AGERE SYSTEMS ]
