Rainbow Electronics DS4520 - Manual (Page 10)

DS4520
9-Bit I
2
C Nonvolatile
I/O Expander Plus Memory
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is a registered trademark of Dallas Semiconductor Corporation.
SLAVE
ADDRESS*
START
START
1 0 1 0 A2 A1 A0 R/W
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
MSB LSB MSB LSB MSB LSB
b7 b6 b5 b4 b3 b2 b1 b0
READ/
WRITE REGISTER ADDRESS
b7 b6 b5 b4 b3 b2 b1 b0
DATA
STOP
SINGLE BYTE WRITE
-WRITE I/O CONTROL 0
REGISTER TO 00h
SINGLE BYTE WRITE
-WRITE PULLUP ENABLE 0
REGISTER TO FFh
SINGLE BYTE READ
-READ I/O STATUS 0 RESISTER
TWO BYTE WRITE
-WRITE I/O CONTROL 0 AND
I/O CONTROL 1 REGISTERS TO 00h
START STOP 1 0 1 0 0 0 0 0 1 1 1 1 0 0 1 0
A0h F2h
START
REPEATED
START
A1h
MASTER
NACK
STOP 1 0 1 0 0 0 0 0 1 1 1 1 1 0 0 0
F8h
1 0 1 0 0 0 0 1
1 0 1 0 0 0 0 0 1 1 1 1 0 0 1 0
A0h F2h
STOP
I/O STATUS
START 1 0 1 0 0 0 0 0 1 1 1 1 0 0 0 0
A0h F0h
STOP
DATA
FFh
00h 00h
EXAMPLE I 2 C TRANSACTIONS (WHEN A0, A1, AND A2 ARE CONNECTED TO GND)
TYPICAL I 2 C WRITE TRANSACTION
*THE SLAVE ADDRESS IS DETERMINED BY ADDRESS PINS A0, A1, AND A2.
0 0 0 0 0 0 0 0
1 1 1 1 1 1 1 1
A0h
0 0 0 0 0 0 0 0
TWO BYTE READ
-READ I/O STATUS 0 AND I/O
STATUS 1 RGISTERS
A)
C)
B)
D)
D)
START STOP 1 0 1 0 0 0 0 0 1 1 1 1 1 0 0 0
A0h F8h A1h
1 0 1 0 0 0 0 1 I/O STATUS 0
DATA
I/O STATUS 1
DATA
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
SLAVE
ACK
MASTER
ACK
MASTER
NACK
REPEATED
START
0 0 0 0 0 0 0 0
Figure 3. I 2 C Communication Examples
See Figure 3 for a read example using the repeated
start condition to specify the starting memory location.
Reading Multiple Bytes from a Slave: The read oper-
ation can be used to read multiple bytes with a single
transfer. When reading bytes from the slave, the master
simply ACKs the data byte if it desires to read another
byte before terminating the transaction. After the mas-
ter reads the last byte it must NACK to indicate the end
of the transfer and generates a stop condition.
Applications Information
Power-Supply Decoupling
To achieve best results, it is highly recommended that a
decoupling capacitor is used on the IC power-supply
pins. Typical values of decoupling capacitors are 0.01µF
and 0.1µF. Use a high-quality, ceramic, surface-mount
capacitor, and mount it as close as possible to the V
CC
and GND pins of the IC to minimize lead inductance.
Chip Topology
TRANSISTOR COUNT: 14,398
SUBSTRATE CONNECTED TO GROUND
Package Information
For the latest package outline information, go to
www.maxim-ic.com/DallasPackInfo .