AN1043 データシートの表示（PDF） - Microchip Technology

部品番号

コンポーネント説明

メーカー

AN1043

Unique Features of the MCP23X08/17 GPIO Expanders

Microchip Technology 

AN1043

HARDWARE ADDRESS PINS

Address pins are typically used on I2C devices to allow

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.

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).

FIGURE 9:

ADDRESS PINS ON SPI DEVICES

CS

SCK

SDI

SDO

MCP23S08

A2

A1 A1

A0 A0

MCP23S17

SPI

Addr

Pins

GPIO

Port

GP15

.

.

.

MCP23S08

.

GP7

.

.

.

.

.

.

GP0 GP0

A2 A1 A0

S 01001000A 00001010A

MCP23X17

Opcode

Register Addr

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

© 2006 Microchip Technology Inc.

Share Link: