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PRELIMINARY
DS3 UNI FOR ATM
XRT7245
REV. 1.03
11
16
D7
I/O
Bi-Directional Data bus (Microprocessor Interface Section):
(Please see descrip-
tion for D15)
17
D6
I/O
Bi-Directional Data bus (Microprocessor Interface Section):
(Please see descrip-
tion for D15)
18
D5
I/O
Bi-Directional Data bus (Microprocessor Interface Section):
(Please see descrip-
tion for D15)
19
D4
I/O
Bi-Directional Data bus (Microprocessor Interface Section):
(Please see descrip-
tion for D15)
20
Width16
I
Microprocessor Interface Block Data Bus Width Selector:
This input pin allows the
user to configure the microprocessor interface of the UNI, to operate over either an 8
or 16 bit wide data bus. Tying this pin to VCC configures the Microprocessor Interface
Data Bus width to be 16 bits. Tying this pin to GND configures the Microprocessor
Interface Data Bus width to be 8 bits.
21
D3
I/O
Bi-Directional Data bus (Microprocessor Interface Section):
(Please see descrip-
tion for D15)
22
Encodis
O
Encoder (B3ZS) Disable Output pin (intended to be connected to the XRT7300
DS3/E3 LIU IC).
This output pin is intended to be connected to the Encodis input pin of the XRT7300
LIU IC. The user can control the state of this output pin by writing a “0” or “1” to Bit 3
(Encodis) of the Line Interface Driver Register (Address = 72h). If the user commands
this signal to toggle “high” then it will disable the B3ZS encoder circuitry within the
XRT7300 IC. Conversely, if the user commands this output signal to toggle “l(fā)ow”, then
the B3ZS Encoder circuitry, within the XRT7300 IC will be enabled.
Writing a “1” to Bit 3 of the Line Interface Driver Register (Address = 72h) will cause this
output pin to toggle “high”. Writing a “0” to this bit-field will cause this output pin to toggle
“l(fā)ow”.
Notes:
1. The user is advised to disable the B3ZS encoder (within the XRT7300 IC) if the
Transmit and Receive DS3 Framers (within the UNI) are configured to operate
in the B3ZS line code.
2. If the customer is not using the XRT7300 DS3 Line Transmitter IC, then he/
she can use this output pin for a variety of other purposes.
23
D2
I/O
Bi-Directional Data bus (Microprocessor Interface Section):
(Please see descrip-
tion for D15)
PIN DESCRIPTION (CONT’D)
P
IN
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YMBOL
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YPE
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ESCRIPTION