MCP4441 datasheet(55/94 Pages) MICROCHIP

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 2010 Microchip Technology Inc.

DS22267A-page 55

MCP443X/5X

7.0

DEVICE COMMANDS

The MCP44XX’s I2C command formats are specified in

this section. The I2C protocol does not specify how

commands are formatted.

The MCP44XX supports four basic commands. The

location accessed determines the commands that are

supported.

For the Volatile Wiper Registers, these commands are:

• Write Data

• Read Data

•Increment Data

•Decrement Data

For the TCON Register, these commands are:

• Write Data

• Read Data

These commands have formats for both a single

command or continuous commands. These commands

are shown in Table 7-1.

Each command has two operational states. These

operational states are referred to as:

• Normal Serial Commands

• High-Voltage Serial Commands

TABLE 7-1:

I2C COMMANDS

Normal serial commands are those where the HVC pin

is driven to VIH or VIL. With High-Voltage Serial

Commands, the HVC pin is driven to VIHH. In each

mode, there are four possible commands.

Table 7-2 shows the supported commands for each

memory location.

Table 7-3 shows an overview of all the device

commands and their interaction with other device

features.

7.1

Command Byte

The MCP44XX’s Command Byte has three fields: the

Address, the Command Operation, and 2 Data bits

(see Figure 7-1). Currently only one of the data bits is

defined (D8).

The device memory is accessed when the Master

sends a proper Command Byte to select the desired

operation. The memory location getting accessed is

contained in the Command Byte’s AD3:AD0 bits. The

action desired is contained in the Command Byte’s

C1:C0 bits, see Figure 7-1. C1:C0 determines if the

desired memory location will be read, written,

Incremented (wiper setting +1) or Decremented (wiper

setting -1). The Increment and Decrement commands

are only valid on the volatile wiper registers, and in

High Voltage commands to enable/disable WiperLock

Technology and Software Write Protect.

If the Address bits and Command bits are not a valid

combination, then the MCP44XX will generate a Not

Acknowledge pulse to indicate the invalid combination.

The I2C Master device must then force a Start

Condition to reset the MCP44XX’s I2C module.

D9 and D8 are the most significant bits for the digital

potentiometer’s wiper setting. The 8-bit devices utilize

D8 as their MSb while the 7-bit devices utilize D7 (from

the data byte) as their MSb.

FIGURE 7-1:

Command Byte Format.

Note:

High Voltage commands are supported for

compatibility with Non-Volatile devices in

the family.

Command

# of Bit Clocks

(1)

Operation

Mode

Write Data

Single

Continuous

18n + 11

Read Data

Single

Random

Continuous

18n + 11

Increment

Single

Continuous

9n + 11

Decrement

Single

Continuous

9n + 11

Note 1:

“n” indicates the number of times the

command operation is to be repeated.

MCP4XXX

COMMAND BYTE

00 = Write Data

01 = Increment

MSbits (Data)

10 = Decrement

11 = Read Data

Command Operation bits

Memory Address

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