Datasheet
Device Address
0 1 0 0
A1A2 A0
Slave Address
R/W
Fixed Programmable
Control Register and Command Byte
0 0 0 B2 B1 B000
PCA9535
SCPS129I – AUGUST 2005 – REVISED MAY 2008 ...........................................................................................................................................................
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Figure 4 shows the address byte of the PCA9535.
Figure 4. PCA9535 Address
Address Reference
INPUTS
I
2
C BUS SLAVE ADDRESS
A2 A1 A0
L L L 32 (decimal), 20 (hexadecimal)
L L H 33 (decimal), 21 (hexadecimal)
L H L 34 (decimal), 22 (hexadecimal)
L H H 35 (decimal), 23 (hexadecimal)
H L L 36 (decimal), 24 (hexadecimal)
H L H 37 (decimal), 25 (hexadecimal)
H H L 38 (decimal), 26 (hexadecimal)
H H H 39 (decimal), 27 (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.
Following the successful acknowledgment of the address byte, the bus master sends a command byte that is
stored in the control register in the PCA9535. Three bits of this data byte state the operation (read or write) and
the internal register (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 command byte has been sent, the register that was addressed continues to be accessed by reads until a
new command byte has been sent.
Figure 5. Control Register Bits
Control Register
CONTROL REGISTER BITS
COMMAND POWER-UP
REGISTER PROTOCOL
BYTE (HEX) DEFAULT
B2 B1 B0
0 0 0 0x00 Input Port 0 Read byte xxxx xxxx
0 0 1 0x01 Input Port 1 Read byte xxxx xxxx
0 1 0 0x02 Output Port 0 Read/write byte 1111 1111
0 1 1 0x03 Output Port 1 Read/write byte 1111 1111
1 0 0 0x04 Polarity Inversion Port 0 Read/write byte 0000 0000
1 0 1 0x05 Polarity Inversion Port 1 Read/write byte 0000 0000
1 1 0 0x06 Configuration Port 0 Read/write byte 1111 1111
1 1 1 0x07 Configuration Port 1 Read/write byte 1111 1111
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