PCA9501_4

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 04 — 10 February 2009

6 of 28

NXP Semiconductors

PCA9501

7.2 Control register

The PCA9501 contains a single 8-bit register called the Control register, which can be

of the slave address.

It contains the I/O operation information.

7.3 I/O operations

(Refer also to Figure 5.)

Each of the PCA9501's eight I/Os can be independently used as an input or output.

Output data is transmitted to the port by the I/O Write mode (see Figure 7). Input I/O data

is transferred from the port to the microcontroller by the Read mode (see Figure 8).

Fig 7.

I/O Write mode (output)

0

A

S

slave address (I/O expander)

START condition

R/W

acknowledge

from slave

002aad290

DATA 1

data to port

A

acknowledge

from slave

12345678

SCL

9

SDA

DATA 2

A

write to port

data out from port

acknowledge

from slave

DATA 2 VALID

data to port

A5 A4 A3 A2 A1 A0

0

DATA 1 VALID

Fig 8.

I/O Read mode (input)

A5 A4 A3 A2 A1 A0

1

A

S0

slave address (I/O expander)

START condition

R/W

acknowledge

from slave

002aad291

data from port

A

acknowledge

from master

SDA

1

no acknowledge

from master

read from

port

data into

port

data from port

DATA 1

DATA 4

INT

DATA 4

DATA 2

DATA 3

P

STOP

condition

12345678

SCL

9

DATA 1