MCP40D18T datasheet(36/66 Pages) MICROCHIP

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MCP40D17/18/19

DS22152B-page 36

5.2.9

I2C COMMAND PROTOCOL

The MCP40D17/18/19 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.

All devices are offered with the I2C slave address of

“0101110”, while the MCP40D18 also offers a second

standard I2C slave address of “0111110”.

FIGURE 5-9:

Slave Address Bits in the

I2C Control Byte (Slave Address = “0101110”).

TABLE 5-2:

DEVICE I2C ADDRESS

5.2.9.2

Hardware Address Pins

The MCP40D17/MCP40D18/MCP40D19 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 MCP40D17/18/19 devices do not respond to

General Call address and commands, and therefore

the communications are Not Acknowledged.

FIGURE 5-10:

General Call Formats.

SA6 A5A4A3A2 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

Comment

MCP40D17

‘0101110’

MCP40D18

‘0101110’

MCP40D18-xxxE/LT

‘0111110’

MCP40D18-xxxAE/LT

MCP40D19

‘0101110’

000

XX0 A

General Call Address

Second Byte

“7-bit Command”

Reserved 7-bit Commands (By I2C Specification - Philips # 9398 393 40011, Ver. 2.1 January 2000)

“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 X

XX X

n occurrences of (Data + A / A)

This indicates a “Hardware General Call”

MCP40D17/18/19 will ignore this byte and

all following bytes (and A), until a Stop bit

(P) is encountered.

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