X9258
Figure 3. Two-Byte Instruction Sequence
SCL
SDA
S
T
A
R
T
0
1
0
1
A3
A2
A1
A0
A
C
K
I3
I2
I1
I0
R1 R0 P1 P0
A
C
K
S
T
O
P
The Increment/Decrement command is different from
the other commands. Once the command is issued
and the X9258 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
terminal.
Table 1. Instruction Set
Instruction Set
Instruction
Read Wiper Counter
Register
Write Wiper Counter
Register
Read Data Register
Write Data Register
XFR Data Register to
Wiper Counter Register
XFR Wiper Counter
Register to Data
Register
Global XFR Data
Registers to Wiper
Counter Registers
Global XFR Wiper
Counter Registers
to Data Register
Increment/Decrement
Wiper Counter Register
Note:
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.
I
3
1
1
1
1
1
I
2
0
0
0
1
1
I
1
0
1
1
0
0
I
0
1
0
1
0
1
R
1
0
0
1/0
1/0
1/0
R
0
0
0
1/0
1/0
1/0
P
1
1/0
1/0
1/0
1/0
1/0
P
0
1/0
1/0
1/0
1/0
1/0
Operation
Read the contents of the Wiper Counter Register
pointed to by P
1
- P
0
Write new value to the Wiper Counter Register
pointed to by P
1
- P
0
Read the contents of the Data Register pointed
to by P
1
- P
0
and R
1
- R
0
Write new value to the Data Register pointed to
by P
1
- P
0
and R
1
- R
0
Transfer the contents of the Data Register pointed
to by P
1
- P
0
and R
1
- R
0
to its associated Wiper
Counter Register
Transfer the contents of the Wiper Counter Reg-
ister pointed to by P
1
- P
0
to the Data Register
pointed to by R
1
- R
0
Transfer the contents of the Data Registers
pointed to by R
1
- R
0
of all four pots to their re-
spective Wiper Counter Registers
Transfer the contents of both Wiper Counter
Registers to their respective data Registers
pointed to by R
1
- R
0
of all four pots
Enable Increment/decrement of the Control Latch
pointed to by P
1
- P
0
1
1
1
0
1/0
1/0
1/0
1/0
0
0
0
1
1/0
1/0
0
0
1
0
0
0
1/0
1/0
0
0
0
0
1
0
0
0
1/0
1/0
(1) 1/0 = data is one or zero
5
FN8168.1
May 6, 2005
INTERSIL [ INTERSIL CORPORATION ]
