Rainbow Electronics MAX7311 - Manual (Page 6)

MAX7311
Detailed Description
The MAX7311 general-purpose input/output (GPIO)
peripheral provides up to 16 I/O ports, controlled
through an I
2 C-compatible serial interface. The
MAX7311 consists of input port registers, output port
registers, polarity inversion registers, configuration reg-
isters, and a bus-timeout register. Upon power-on, all
I/O lines are set as inputs. Three slave ID address select
pins, AD0, AD1, and AD2, choose one of 64 slave ID
addresses, including the eight addresses supported by
the Phillips PCA9555. Table 1 is the register address
table. Tables 2–6 show detailed register information.
Serial Interface
Serial Addressing
The MAX7311 operates as a slave that sends and
receives data through a 2-wire interface. The interface
uses a serial data line (SDA) and a serial clock line
(SCL) to achieve bidirectional communication between
master(s) and slave(s). A master, typically a microcon-
troller, initiates all data transfers to and from the
MAX7311, and generates the SCL clock that synchro-
nizes the data transfer (Figure 2).
2-Wire-Interfaced 16-Bit I/O Port Expander
with Interrupt
6 _______________________________________________________________________________________
I/O0
I/O1
I/O2
I/O3
I/O4
I/O5
I/O6
I/O7
INPUT/OUTPUT
PORT 1
SMBus
CONTROL
8 BIT
READ PULSE
WRITE PULSE
I/O8
I/O9
I/O10
I/O11
I/O12
I/O13
I/O14
I/O15
INPUT/OUTPUT
PORT 2
8 BIT
READ PULSE
WRITE PULSE
INT POWER-ON
RESET
INPUT
FILTER
N
V +
SDA
SCL
AD2
AD1
AD0
GND
MAX7311
Figure 1. MAX7311 Block Diagram
SCL
SDA
START CONDITION STOP CONDITION REPEATED START CONDITION START CONDITION
t SU, DAT
t HD, DAT
t LOW
t HD, STA
t HIGH
t R t F
t SU, STA
t HD, STA
t SU, STO
t BUF
Figure 2. 2-Wire Serial Interface Timing Diagram