MCP23008/MCP23S08 - Microchip

MCP23008/MCP23S08
1.4.1 ADDRESSING I 2 C DEVICES
(MCP23008)
The MCP23008 is a slave I 2 C device that supports 7-bit
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). Figure 1-2 shows the control byte format.
1.4.2 ADDRESSING SPI DEVICES
(MCP23S08)
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. Figure 1-3 shows
the control byte format.
FIGURE 1-4: I 2 C ADDRESSING REGISTERS
FIGURE 1-5: SPI ADDRESSING REGISTERS
CS
FIGURE 1-2: I 2 C CONTROL BYTE
FORMAT
S 0 1 0 0 A2 A1 A0 R/W ACK
FIGURE 1-3: SPI CONTROL BYTE
FORMAT
DS21919E-page 8 © 2007 Microchip Technology Inc.
Start
bit
CS
Control Byte
Slave Address
R/W = 0 = write
R/W = 1 = read
Control Byte
R/W bit
ACK bit
0 1 0 0 0 A1 A0 R/W
Slave Address
R/W = 0 = write
R/W = 1 = read
R/W bit
S 0 1 0 0 A2 A1 A0 0 ACK A7 A6 A5 A4 A3 A2 A1 A0 ACK
R/W = 0
Device Opcode Register Address
The ACKs are provided by the MCP23008.
0 1 0 0 0 A1 A0 R/W A7 A6 A5 A4 A3 A2 A1 A0
Device Opcode Register Address