ISL95711 Intersil Corporation, ISL95711 Datasheet - Page 10

• Manufacturer Part Number: ISL95711
• Description: 128 Taps I2C Serial Interface
• Manufacturer: Intersil Corporation

Communicating with the ISL95711
There are 3 register addresses in the ISL95711, of which two
can be used. Address 00h and address 02h are used to
control the device. Address 01h is reserved and should not
be used. Address 00h contains the non-volatile Initial Value
Register (IVR), and the volatile Wiper Register (WR).
Address 02h contains only a volatile word and is used as a
pointer to either the IVR or WR. See Table 1.
Register Descriptions: Access Control
The Access Control Register (ACR) is volatile and is at
address 02h. It is 8-bits, and only the MSB is significant, all
other bits should be zero (0). The ACR controls which word
is accessed at register 00h as follows:
00h = Nonvolatile IVR
80h = Volatile WR
All other bits of the ACR should be written to as zeros. Only
the MSB can be either 0 or 1. Power-up default for this
address is 00h.
Register Description: IVR and WR
The ISL95711 has a single potentiometer. The wiper of the
potentiometer is controlled directly by the WR. Writes and
reads can be made directly to this register to control and
monitor the wiper position without any non-volatile memory
changes. This is done by setting address 02h to data 80h,
then writing the data.
SIGNAL AT SDA
FROM THE
SIGNALS
MASTER
SIGNALS FROM
THE SLAVE
S
T
A
R
T
0
IDENTIFICATION
1
BYTE WITH
SIGNALS FROM
SIGNAL AT SDA
SIGNALS FROM
0
R/W=0
THE MASTER
THE ISL95711
1
10
0
A
1
A
0
0
A
C
K
0 0 0
ADDRESS
S
A
R
T
T
BYTE
0
0
FIGURE 3. BYTE WRITE SEQUENCE
IDENTIFICATION
0 0
1
FIGURE 4. READ SEQUENCE
0
BYTE
1
0
0
A
C
K
A
1
ISL95711
A
S
A
R
T
T
0
WRITE
0
0
IDENTIFICATION
A
C
K
1
BYTE WITH
0
0 0 0 0
R/W=1
1
ADDRESS
The non-volatile IVR stores the power-up value of the wiper.
On power-up, the contents of the IVR are transferred to the
WR.
To write to the IVR, first address 02h is set to data 00h, then
the data is written. Writing a new value to the IVR register
will set a new power-up position for the wiper. Also, writing to
this register will load the same value into the WR as the IVR.
So, if a new value is loaded into the IVR, not only will the
non-volatile IVR change, but the WR will also contain the
same value after the write, and the wiper position will
change. Reading from the IVR will not change the WR, if its
contents are different.
0
BYTE
A
0 0 0 0
1
A
0
1
A
C
K
0
A
C
K
FIRST READ
DATA BYTE
DATA
BYTE
A
C
K
A
C
K
A
C
K
S
T
O
P
LAST READ
DATA BYTE
August 15, 2005
FN8241.2
O
S
T
P