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Device Address

0

1

0

0

A1

A2

A0

Slave Address

R/W

Fixed

Hardware

Selectable

Control Register and Command Byte

0

0

0

0

B1

B0

0

0

PCA9534

WITH INTERRUPT OUTPUT AND CONFIGURATION REGISTERS

SCPS124B – SEPTEMBER 2006 – REVISED FEBRUARY 2007

Interface Definition

BIT

BYTE

7 (MSB)

6

5

4

3

2

1

0 (LSB)

L

H

L

L

A2

A1

A0

R/W

Px I/O data bus

P7

P6

P5

P4

P3

P2

P1

P0

Figure 4 shows the address byte of the PCA9534.

Figure 4. PCA9534 Address

Address Reference

INPUTS

A2

A1

A0

L

L

L

32 (decimal), 20 (hexadecimal)

L

L

H

33 (decimal), 21 (hexadecimal)

L

H

L

34 (decimal), 22 (hexadecimal)

L

H

H

35 (decimal), 23 (hexadecimal)

H

L

L

36 (decimal), 24 (hexadecimal)

H

L

H

37 (decimal), 25 (hexadecimal)

H

H

L

38 (decimal), 26 (hexadecimal)

H

H

H

39 (decimal), 27 (hexadecimal)

The last bit of the slave address defines the operation (read or write) to be performed. When it is high (1), a read

is selected, while a low (0) selects a write operation.

Following the successful acknowledgment of the address byte, the bus master sends a command byte, which is

stored in the control register in the PCA9534. Two bits of this command byte state the operation (read or write)

and the internal register (input, output, polarity inversion or configuration) that will be affected. This register can

Once a command byte has been sent, the register that was addressed continues to be accessed by reads until

a new command byte has been sent.

Figure 5. Control Register Bits

6

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