MCP23X08EV Microchip Technology, MCP23X08EV Datasheet - Page 8

• Manufacturer Part Number: MCP23X08EV
• Description: BOARD EVALUATION FOR MCP23X08
• Manufacturer: Microchip Technology

Specifications of MCP23X08EV

• Main Purpose: Interface, GPIO Expander
• Utilized Ic / Part: MCP23008, MCP23S08
• Processor To Be Evaluated: MCP23008 and MCP23S08
• Data Bus Width: 8 bit
• Interface Type: SPI
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

AN1043
HARDWARE ADDRESS PINS
Address pins are typically used on I
multiple devices with the same base slave address to
operate on the bus.
Slave devices with SPI interfaces typically use only a
chip select pin to select the device. This requirement
consumes one MCU pin for every SPI device on the
bus.
FIGURE 9:
SUMMARY
The MCP23X08/17 family of GPIO Expanders have
some unique features, giving the system and module
engineer maximum flexibility when designing with the
MCP23X08/17.
DS01043A-page 8
ADDRESS PINS ON SPI DEVICES
MCP23S08
A1
A0
2
C devices to allow
A2
A1
A0
SDO
SCK
SDI
S
CS
0 1 0 0 1
MCP23X17
MCP23S17
Addr
Pins
Opcode
SPI
A2 A1 A0
0
0
The “S” devices (MCP23S08 and MCP23S17) have
SPI interfaces. These devices use a chip select for
selecting the part, however, these parts also have hard-
ware address pins, thereby giving the advantage of
attaching multiple devices on the bus while only
consuming one MCU pin for chip select (see Figure 9).
GPIO
Port
0 A
0 0 0 0 1
GP15
.
.
.
.
.
.
.
GP0
Register Addr
MCP23S08
0
GP7
.
.
.
GP0
1
0 A
© 2006 Microchip Technology Inc.