MCP23008 Microchip Technology, MCP23008 Datasheet - Page 8

• Manufacturer Part Number: MCP23008
• Description: 8-Bit I/O Expander with Serial Interface
• Manufacturer: Microchip Technology

MCP23008/MCP23S08
1.4.1
The MCP23008 is a slave I
slave addressing, with the read/write bit filling out the
control byte. The slave address contains four fixed bits
and three user-defined hardware address bits (pins A2,
A1 and A0).
1.4.2
The MCP23S08 is a slave SPI device. The slave
address contains five fixed bits and two user-defined
hardware address bits (pins A1 and A0), with the read/
write bit filling out the control byte.
the control byte format.
FIGURE 1-4:
FIGURE 1-5:
DS21919D-page 8
CS
S
0
0
ADDRESSING I
(MCP23008)
ADDRESSING SPI DEVICES
(MCP23S08)
Figure 1-2
1
1
Device Opcode
Device Opcode
0
0
I
SPI ADDRESSING REGISTERS
shows the control byte format.
2
C™ ADDRESSING REGISTERS
0
0
2
C device that supports 7-bit
A2 A1 A0
2
0
C DEVICES
The ACKs are provided by the MCP23008.
A1 A0 R/W
Figure 1-3
R/W = 0
0
shows
ACK
A7
A7
FIGURE 1-2:
FIGURE 1-3:
A6
A6
Start
bit
CS
S
A5
A5
0
0
R/W = 0 = write
R/W = 1 = read
Register Address
Register Address
R/W = 0 = write
R/W = 1 = read
1
A4
1
A4
Slave Address
Slave Address
0
0
Control Byte
Control Byte
A3
A3
I
FORMAT
SPI CONTROL BYTE
FORMAT
0
2
0
© 2007 Microchip Technology Inc.
C™ CONTROL BYTE
A2
A2
A2 A1 A0 R/W ACK
0
R/W bit
ACK bit
R/W bit
A1 A0 R/W
A1
A1
A0
A0
ACK