MCP4432 datasheet(69/100 Pages) MICROCHIP

69 / 100 page

DS22265A-page 69

MCP444X/446X

7.6

Increment Wiper

Normal and High Voltage

The Increment Command provides a quick and easy

method to modify the potentiometer’s wiper by +1 with

minimal overhead. The Increment Command will only

function on the volatile wiper setting memory locations

00h, 01h, 06h and 07h. The Increment Command to

Nonvolatile addresses will be ignored and will generate

a A.

When executing an Increment Command, the volatile

wiper setting will be altered from n to n+1 for each

Increment Command received. The value will

increment up to 100h max on 8-bit devices and 80h on

7-bit devices. If multiple Increment Commands are

received after the value has reached 100h (or 80h), the

value will not be incremented further. Table 7-4 shows

the Increment Command versus the current volatile

wiper value.

The Increment Command will most commonly be

performed on the Volatile Wiper locations until a

desired condition is met. The value in the Volatile Wiper

in order to write the new setting to the corresponding

Nonvolatile wiper memory using a Write operation. The

MCP44XX is responsible for generating the A bits.

Refer to Figure 7-7 for the Increment Command

sequence. The sequence is terminated by the Stop

condition. So when executing a continuous command

string, the Increment command can be followed by any

other valid command. This means that writes do not

need to be to the same volatile memory address.

The advantage of using an Increment Command

instead of a read-modify-write series of commands is

speed and simplicity. The wiper will transition after each

Command Acknowledge when accessing the volatile

wiper registers.

TABLE 7-4:

INCREMENT OPERATION VS.

VOLATILE WIPER VALUE

7.6.1

THE HIGH VOLTAGE COMMAND

(HVC) SIGNAL

The High Voltage Command (HVC) signal is

multiplexed with Address 0 (A0) and is used to indicate

that the command, or sequence of commands, are in

the High Voltage mode. Signals > VIHH (~8.5V) on the

HVC/A0 pin puts MCP44XX devices into High Voltage

mode. High Voltage commands allow the device’s

WiperLock Technology and write protect features to be

enabled and disabled.

The HVC pin has an internal resistor connection to the

MCP44XX’s internal VDD signal.

FIGURE 7-7:

I2C Increment Command Sequence.

Note:

Table 7-4 shows the valid addresses for

the Increment Wiper command. Other

addresses are invalid.

Note:

The command sequence can go from an

increment to any other valid command for

the

specified

address.

Issuing

increment or decrement to a nonvolatile

location will cause an error condition (A

will be generated).

Current Wiper

Setting

Wiper (W)

Properties

Increment

Command

Operates?

7-bit

Pot

8-bit

Pot

3FFh

081h

3FFh

101h

Reserved

(Full-Scale (W = A))

080h

100h

Full-Scale (W = A)

07Fh

041h

0FFh

081

W = N

040h

080h

W = N (Mid-Scale) Yes

03Fh

001h

07Fh

001

W = N

000h

Zero Scale (W = B) Yes

Note:

There is a required delay after the HVC pin

is driven to the VIHH level to the 1st edge

of the SCL pin.

Control Byte

INCR Command (n+1)

INCR Command (n+2)

010

1 A1 A0 0

AD AD AD AD

A1 x

X A

AD AD AD AD

X A P (2)

43 21

Fixed

Address

Variable

Address

Device

Memory

Address

Command

Write bit

Note1:

Increment Command (INCR) only functions when accessing the volatile wiper

registers (AD3:AD0 = 00h, 01h, 06h, and 07h).

This command sequence does not need to terminate (using the Stop bit) and can

change to any other desired command sequence (Increment, Read, or Write).

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