MCP4716 datasheet(32/70 Pages) MICROCHIP

32 / 70 page

MCP47A1

DS25154A-page 32

 2012 Microchip Technology Inc.

5.2.9

I2C COMMAND PROTOCOL

The MCP47A1 is a slave I2C device which supports 7-

bit slave addressing. The slave address contains seven

fixed bits. Figure 5-9 shows the control byte format.

5.2.9.1

Control Byte (Slave Address)

The Control Byte is always preceded by a START

condition. The Control Byte contains the slave address

consisting of seven fixed bits and the R/W bit. Figure 5-

9 shows the control byte format and Table 5-2 shows

the I2C address for the devices.

FIGURE 5-9:

Slave Address Bits in the

I2C Control Byte.

TABLE 5-2:

DEVICE I2C ADDRESS

5.2.9.2

Hardware Address Pins

The MCP47A1 does not support hardware address

bits.

5.2.10

GENERAL CALL

The General Call is a method that the Master device

can communicate with all other Slave devices.

The MCP47A1 devices do not respond to General Call

address

and

commands,

and

therefore

the

communications are Not Acknowledged.

FIGURE 5-10:

General Call Formats.

S A6A5 A4A3A2 A1A0 R/W A/A

Start

bit

Slave Address

R/W bit

A bit (controlled by slave device)

R/W = 0 = write

R/W = 1 = read

A = 0 = Slave Device Acknowledges byte

A = 1 = Slave Device does not Acknowledge byte

“0” “1” “0” “1” “1” “1” “0”

Device

I2C Address

Binary

Hex (1) Code Comment

MCP47A1

‘0101110’0x5C

‘0111110’0x7C

Note 1: The LSb of the 8-bit hex code is the I2C

Read/Write (R/W) bit. This hex value has

a R/W bit = “0” (write). If the R/W bit

reflected a read, these values would be

0x5D and 0x7D.

Note 1: The MCP47A1 device supports two differ-

ent I2C address (A0 and A1). This allows

two MCP47A1 devices on the same I2C

bus.

000

X XXX

General Call Address

Second Byte

“7-bit Command”

Reserved 7-bit Commands (By I2C Specification - NXP specification # UM10204, Ver. 03 16 January 2007)

“0000 011”b

- Reset and write programmable part of slave address by hardware

“0000 010”b

- Write programmable part of slave address by hardware

“0000 000”b

- NOT Allowed

The Following is a “Hardware General Call” Format

000

X XXX

XX1A

General Call Address

Second Byte

“7-bit Command”

X XXX

XX X

n occurrences of (Data + A / A)

This indicates a “Hardware General Call”.

MCP47A1 will ignore this byte and

all following bytes (and A), until

a Stop bit (P) is encountered.

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