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REMOTE 8-BIT I C AND SMBus LOW-POWER I/O EXPANDER
WITH INTERRUPT OUTPUT, RESET, AND CONFIGURATION REGISTERS
2
SCPS139B – JANUARY 2006 – REVISED OCTOBER 2006
Device Address
The address of the PCA6107 is shown in
Slave Address
0
0
1
1 A2 A1 A0 R/W
Programmable
Fixed
Figure 4. PCA6107 Address
Address Reference
INPUTS
A2
L
L
L
L
H
H
H
H
A1
L
L
H
H
L
L
H
H
A0
L
H
L
H
L
H
L
H
I
2
C BUS SLAVE ADDRESS
24 (decimal), 18 (hexadecimal)
25 (decimal), 19 (hexadecimal)
26 (decimal), 1A (hexadecimal)
27 (decimal), 1B (hexadecimal)
28 (decimal), 1C (hexadecimal)
29 (decimal), 1D (hexadecimal)
30 (decimal), 1E (hexadecimal)
31 (decimal), 1F (hexadecimal)
The last bit of the slave address defines the operation (read or write) to be performed. A high (1) selects a read
operation, while a low (0) selects a write operation.
Control Register and Command Byte
Following the successful acknowledgment of the address byte, the bus master sends a command byte that is
stored in the control register in the PCA6107. Two bits of this data byte state the operation (read or write) and
the internal registers (input, output, polarity inversion or configuration) that will be affected. This register can be
written or read through the I
2
C bus. The command byte is sent only during a write transmission.
Once a new command byte has been sent, the register that was addressed continues to be accessed by reads
until a new command byte has been sent.
0
0
0
0
0
0
B1
B0
Figure 5. Control Register Bits
Command Byte
CONTROL REGISTER BITS
B1
0
0
1
1
B0
0
1
0
1
COMMAND BYTE
(HEX)
0x00
0x01
0x02
0x03
REGISTER
Input Port
Output Port
Polarity Inversion
Configuration
PROTOCOL
Read byte
Read/write byte
Read/write byte
Read/write byte
POWER-UP
DEFAULT
xxxx xxxx
0000 0000
1111 0000
1111 1111
7
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