X9440 datasheet(6/21 Pages) INTERSIL

6 / 21 page

FN8200.0

March 28, 2005

Four of the ten instructions end with the transmission

of the instruction byte. The basic sequence is illus-

trated in Figure 4. These two-byte instructions

exchange data between the wiper counter register or

analog control register and one of the data registers. A

transfer from a data register to a wiper counter register

or analog control register is essentially a write to a

static RAM. The response of the wiper to this action

will be delayed tWRL. A transfer from the wiper counter

write to non volatile memory and takes a minimum of

tWR to complete. The transfer can occur between one

of the two potentiometers or one of the two voltage

comparators and one of its associated registers; or it

may occur globally, wherein the transfer occurs

between both of the potentiometers and voltage com-

parators and one of their associated registers.

Five instructions require a three-byte sequence to

complete. These instructions transfer data between

the host and the X9440; either between the host and

one of the data registers or directly between the host

and the wiper counter and analog control registers.

These instructions are: Read Wiper Counter Register

or Analog Control Register, read the current wiper

position of the selected pot or the comparator control

bits, Write Wiper Counter Register or Analog Control

selected pot or control the voltage comparator; Read

Data Register, read the contents of the selected non

volatile register; Write Data Register, write a new value

to the selected data register. The bit structures of the

instructions are shown in Figure 9.

The sequences of the three byte operations are shown

in Figure 5 and Figure 6.

The bit structures of the instructions and the descrip-

tion of the instructions are shown in Figure 10.

Figure 4. Two-Byte Command Sequence

Figure 5. Three-Byte Command Sequence (Write)

0101

00A1

P1 P0

SCK

101

A1 A0

I1 I0

R1 R0 P1 P0

SCL

D5 D4 D3 D2

D1 D0

X9440

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