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Control Register and Command Byte

0

0

0

0

B1

B0

0

0

PCA9536

WITH CONFIGURATION REGISTERS

SCPS125C – APRIL 2006 – REVISED NOVEMBER 2006

The slave address equates to 65 (decimal) and 41 (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 that is

stored in the control register in the PCA9536. Two bits of this data byte state the operation (read or write) and

the internal register (Input, Output, Polarity Inversion, or Configuration) that will be affected. This register can be

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

Command Byte

CONTROL REGISTER BITS

COMMAND BYTE

POWER-UP

REGISTER

PROTOCOL

(HEX)

DEFAULT

B1

B0

0

0

0x00

Input Port

Read byte

1111 XXXX

0

1

0x01

Output Port

Read/write byte

1111 1111

1

0

0x02

Polarity Inversion

Read/write byte

0000 0000

1

1

0x03

Configuration

Read/write byte

1111 1111

6

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