TCA9555_16 Datasheet, PDF (23/46 Pages) Texas Instruments – Low-Voltage 16-Bit I2C and SMBus I/O Expander with Interrupt Output and Configuration Registers

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Programming (continued)
9.5.3 Device Address
Figure 32 shows the address byte of the TCA9555.
R/W
Slave Address
0 1 0 0 A2 A1 A0
TCA9555
SCPS200D – JULY 2009 – REVISED JULY 2016
Fixed Programmable
Figure 32. TCA9555 Address
Table 2 shows the TCA9555 address reference.
Table 2. Address Reference
INPUTS
A2
A1
A0
L
L
L
L
L
H
L
H
L
L
H
H
H
L
L
H
L
H
H
H
L
H
H
H
I²C BUS SLAVE ADDRESS
32 (decimal), 0x20 (hexadecimal)
33 (decimal), 0x21 (hexadecimal)
34 (decimal), 0x22 (hexadecimal)
35 (decimal), 0x23 (hexadecimal)
36 (decimal), 0x24 (hexadecimal)
37 (decimal), 0x25 (hexadecimal)
38 (decimal), 0x26 (hexadecimal)
39 (decimal), 0x27 (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.
9.5.4 Control Register and Command Byte
Following the successful acknowledgment of the address byte, the bus master sends a command byte shown in
Table 3, that is stored in the control register in the TCA9555. Three bits of this data byte state the operation
(read or write) and the internal register (input, output, polarity inversion, or configuration) that is affected. This
register can be written or read through the I²C bus. The command byte is sent only during a write transmission.
When 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 33 shows the control register bits.
0 0 0 0 0 B2 B1 B0
Figure 33. Control Register Bits
CONTROL REGISTER BITS
B2
B1
B0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
Table 3. Command Byte
COMMAND
BYTE (HEX)
0x00
0x01
0x02
0x03
0x04
0x05
REGISTER
Input Port 0
Input Port 1
Output Port 0
Output Port 1
Polarity Inversion Port 0
Polarity Inversion Port 1
PROTOCOL
Read byte
Read byte
Read-write byte
Read-write byte
Read-write byte
Read-write byte
POWER-UP
DEFAULT
xxxx xxxx
xxxx xxxx
1111 1111
1111 1111
0000 0000
0000 0000
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