X9429 Datasheet, PDF (7/21 Pages) Intersil Corporation – Single Digitally Controlled Potentiometer

Figure 3. Two-Byte Instruction Sequence
SCL
X9429
SDA
S 0 1 0 1 A3 A2 0 A0 A I3 I2 I1 I0 R1 R0 0 0 A S
T
C
CT
A
K
KO
R
P
T
Read Wiper Counter Register (read the current wiper
position of the selected pot), write Wiper Counter
Register (change current wiper position of the selected
pot), read Data Register (read the contents of the
selected nonvolatile register) and write Data Register
(write a new value to the selected Data Register). The
sequence of operations is shown in Figure 4.
The Increment/Decrement command is different from
the other commands. Once the command is issued
and the X9429 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
(t_HIGH) while SDA is HIGH, the selected wiper will
move one resistor segment towards the V_H/R_H
terminal. Similarly, for each SCL clock pulse while
SDA is LOW, the selected wiper will move one resistor
segment towards the V_L/R_L 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 Set
Instruction
Read Wiper Counter
Register
I₃ I₂ I₁ I₀ R₁ R₀ X₁ X₀
Operation
1 0 0 1 0 0 0 0 Read the contents of the Wiper Counter Register
Write Wiper Counter
Register
1 0 1 0 0 0 0 0 Write new value to the Wiper Counter Register
Read Data Register
1 0 1 1 1/0 1/0 0
Write Data Register
1 1 0 0 1/0 1/0 0
XFR Data Register to
Wiper Counter Register
1
1
0
1 1/0 1/0
0
XFR Wiper Counter
Register to Data Regis-
ter
1 1 1 0 1/0 1/0 0
0
Read the contents of the Data Register pointed to
by R₁ - R₀
0
Write new value to the Data Register pointed to by
R₁ - R₀
0
Transfer the contents of the Data Register pointed
to by R₁ - R₀ to its Wiper Counter Register
0
Transfer the contents of the Wiper Counter Register
to the Data Register pointed to by R₁ - R₀
Increment/Decrement
Wiper Counter Register
0
0
1
0
0
0
0
0
Enable Increment/decrement of the Wiper Counter
Register
Note: (1) 1/0 = data is one or zero
7
FN8248.2
October 19, 2005