5

FN8164.7

August 17, 2015

from WCR current wiper position to a Data Register is a write

complete. The transfer can occur between one of the four

potentiometers and one of its associated registers; or it may

occur globally, wherein the transfer occurs between all four of

the potentiometers and one of their associated registers.

Four instructions require a three-byte sequence to complete.

These instructions transfer data between the host and the

X9241A; either between the host and one of the Data

Registers or directly between the host and the WCR. These

instructions are: Read WCR, read the current wiper position

of the selected pot; Write WCR, change current wiper

position of the selected pot; Read Data Register, read the

contents of the selected nonvolatile register; 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

X9241A 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.

selected wiper will move one resistor segment towards the

SDA is LOW, the selected wiper will move one resistor

of the sequence and timing for this operation is shown in

Figures 5 and 6 respectively.

S

T

A

R

T

0101

A3

A2

A1

A0

A

I3

I2

I1

I0

P1

P0

R1

R0

SCL

SDA

S

T

O

P

C

K

A

C

K

FIGURE 3. TWO-BYTE INSTRUCTION SEQUENCE

S

T

A

R

T

0

1

0

1

A3 A2 A1 A0

A

I3

I2

I1

I0

P1 P0 R1 R0

SCL

SDA

S

T

O

P

CM DW D5 D4 D3 D2

D1 D0

C

K

A

C

K

A

C

K

FIGURE 4. THREE-BYTE INSTRUCTION SEQUENCE

S

T

A

R

T

0

1

0

1

A3

A2A1A0

I3

I2

I1

I0

P1 P0

R1 R0

SCL

SDA

S

T

O

P

X

X

I

N

C

1

I

N

C

2

I

N

C

n

D

E

C

1

D

E

C

n

A

C

K

A

C

K

FIGURE 5. INCREMENT/DECREMENT INSTRUCTION SEQUENCE

X9241A