XRT73LC03A Datasheet, PDF (59/61 Pages) Exar Corporation – 3 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT

XRT73LC03A
3 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT
REV. 1.0.1
the desired eight bit data word to the SDI input pin via
the Microprocessor Serial Interface. The Micropro-
cessor Serial Interface latches the value on the SDI
input pin on the rising edge of SClk. Apply this word
(D0 through D7) serially, in ascending order with the
LSB first.
Simplified Interface Option
The design of the circuitry connecting to the Micro-
processor Serial Interface can be simplified by tying
both the SDO and SDI pins together and reading data
from and/or writing data to this combined signal. This
simplification is possible because only one of these
signals are active at any given time. The inactive sig-
nal is tri-stated.
NOTES:
1. A5 is always "0"
2. R/W = "1" for Read Operations
3. R/W = "0" for Write Operations
4. Shaded box denotes a “don't care” value
FIGURE 37. MICROPROCESSOR SERIAL INTERFACE DATA STRUCTURE
CS
SClk
SDI
SDO
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
R/W A0 A1 A2 A3 A4 0 A6 D0 D1 D2 D3 D4 D5 D6 D7
High Z
High Z
D0 D1 D2 D3 D4 0 0 0
FIGURE 38. TIMING DIAGRAM FOR THE MICROPROCESSOR SERIAL INTERFACE
CS
SCLK
SDI
t21
t22
t23
t24
R/W
t27
t25
t26
A0
A1
t29
t28
CS
SCLK
t30
t31
SDO _Hi-Z
D0
D1
Hi-Z
SDI
t33
D2
t32
D7
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