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X9408 Datasheet, PDF (6/21 Pages) Intersil Corporation – Low Noise/Low Power/2-Wire Bus
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Figure 3. Two-Byte Instruction Sequence
X9408
SCL
SDA
S 0 1 0 1 A3 A2 A1 A0 A I3 I2 I1 I0 R1 R0 P1 P0 A S
T
C
CT
A
K
KO
R
P
T
The Increment/Decrement command is different from
the other commands. Once the command is issued
and the X9408 has responded with an acknowledge,
the master can clock the selected wiper up and/or
down in one segment steps; thereby, providing a fine
tuning capability to the host. For each SCL clock pulse
(tHIGH) while SDA is HIGH, the selected wiper will
move one resistor segment towards the RH terminal.
Similarly, for each SCL clock pulse while SDA is LOW,
the selected wiper will move one resistor segment
towards the RL terminal. A detailed illustration of the
sequence and timing for this operation are shown in
Figures 5 and 6 respectively.
Table 1. Instruction Set
Instruction
Read Wiper Counter
Register
Write Wiper Counter
Register
Read Data Register
I3 I2
10
10
10
Write Data Register
11
XFR Data Register to 1 1
Wiper Counter Register
XFR Wiper Counter
Register to Data
Register
11
Global XFR Data Regis- 0 0
ters to Wiper Counter
Registers
Global XFR Wiper
Counter Registers to
Data Register
10
Increment/Decrement 0 0
Wiper Counter Register
Note: (7) 1/0 = data is one or zero
Instruction Set
I1 I0 R1 R0 P1
0 1 0 0 P1
1 0 0 0 P1
1 1 R1 R0 P1
0 0 R1 R0 P1
0 1 R1 R0 P1
1 0 R1 R0 P1
0 1 R1 R0 0
0 0 R1 R0 0
1 0 0 0 P1
P0
Operation
P0 Read the contents of the Wiper Counter Register
pointed to by P1 - P0
P0 Write new value to the Wiper Counter Register pointed
to by P1 - P0
P0 Read the contents of the Data Register pointed to by
P1 - P0 and R1 - R0
P0 Write new value to the Data Register pointed to by
P1 - P0 and R1 - R0
P0 Transfer the contents of the Data Register pointed to
by P1 - P0 and R1 - R0 to its associated Wiper Counter
Register
P0 Transfer the contents of the Wiper Counter Register
pointed to by P1 - P0 to the Data Register pointed to
by R1 - R0
0 Transfer the contents of the Data Registers pointed to by
R1 - R0 of all four pots to their respective Wiper Counter
Registers
0 Transfer the contents of both Wiper Counter Registers
to their respective Data Registers pointed to by
R1 - R0 of all four pots
P0 Enable Increment/decrement of the Wiper Counter
Register pointed to by P1 - P0
6
FN8191.2
September 19, 2005
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