MCP23008 Microchip Technology, MCP23008 Datasheet - Page 7

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

FIGURE 1-1:
1.3.3.3
For sequential operations, instead of deselecting the
device by raising CS, the master clocks the next byte
pointed to by the address pointer.
The sequence ends by the raising of CS.
The MCP23S08 address pointer will roll over to
address zero after reaching the last register address.
© 2007 Microchip Technology Inc.
SR
w
S
P
R
ADDR
D
D
OP
OUT
IN
- START
- RESTART
- STOP
- Read
- Write
- Data out from MCP23008
- Data into MCP23008
- Device opcode
SPI Sequential Write/Read
- Device address
Sequential
Sequential
Byte
Byte
MCP23008 I
S
S
S
S
S
S
OP
OP
OP
OP
OP
OP
2
C™ DEVICE PROTOCOL
W
R
W
W
W
W
ADDR
Byte and Sequential Write
Byte and Sequential Read
ADDR
ADDR
SR
SR
SR
OP
OP
MCP23008/MCP23S08
OP
SR
SR
P
SR
1.4
The hardware address pins are used to determine the
device address. To address a device, the correspond-
ing address bits in the control byte must match the pin
state.
• MCP23008 has address pins A2, A1 and A0.
• MCP23S08 has address pins A1 and A0.
The pins must be biased externally.
D
P
R
R
D
IN
OUT
D
D
W
OP
OP
IN
IN
OP
D
D
....
OUT
OUT
Hardware Address Decoder
ADDR
....
....
R
W
R
D
....
D
IN
OUT
D
D
D
D
P
OUT
IN
D
IN
OUT
P
D
IN
OUT
....
....
....
....
P
P
D
D
D
OUT
D
P
IN
OUT
IN
P
DS21919D-page 7
P
P
P
P