0

1

1

1

A1

A2

A0

Slave Address

R/W

Fixed

Hardware

Selectable

0

0

0

0

B1

B0

0

0

PCA9534A

www.ti.com

SCPS141F – SEPTEMBER 2006 – REVISED JUNE 2010

Table 3. Interface Definition

BIT

BYTE

7 (MSB)

6

5

4

3

2

1

0 (LSB)

L

H

H

H

A2

A1

A0

R/W

Px I/O data bus

P7

P6

P5

P4

P3

P2

P1

P0

Device Address

Figure 4 shows the address byte of the PCA9534A.

Figure 4. PCA9534A Address

Table 4. Address Reference

INPUTS

A2

A1

A0

L

L

L

56 (decimal), 38 (hexadecimal)

L

L

H

57 (decimal), 39 (hexadecimal)

L

H

L

58 (decimal), 3A (hexadecimal)

L

H

H

59 (decimal), 3B (hexadecimal)

H

L

L

60 (decimal), 3C (hexadecimal)

H

L

H

61 (decimal), 3D (hexadecimal)

H

H

L

62 (decimal), 3E (hexadecimal)

H

H

H

63 (decimal), 3F (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.

Control Register and Command Byte

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

stored in the control register in the PCA9534A. 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

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