PCA9537_5

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 05 — 7 May 2009

9 of 24

NXP Semiconductors

PCA9537

Fig 7.

Read from register

A

S

START condition

R/W

acknowledge

from slave

002aae638

A

acknowledge

from slave

SDA

A

P

acknowledge

from master

DATA (first byte)

slave address

STOP

condition

S

(repeated)

START condition

(cont.)

(cont.)

0010011

A

1

R/W

acknowledge

from slave

slave address

at this moment master-transmitter becomes master-receiver

and slave-receiver becomes slave-transmitter

NA

no acknowledge

from master

COMMAND BYTE

001001

1

0

data from register

DATA (last byte)

data from register

This figure assumes the command byte has previously been programmed with 00h.

Transfer of data can be stopped at any moment by a STOP condition.

Expanded diagram is shown in Figure 15.

Fig 8.

Read input port register

0010011

A

S1

slave address

START condition

R/W

acknowledge

from slave

002aae639

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