MCP23008 Expander: Features, Pinout, and Datasheet

For I²C bus or SPI applications, the MCP23008 device provides 8-bit general-purpose parallel I/O expansion. The serial interface and the number of hardware address pins on the device are different:

• I²C interface MCP23008; three address pins

For input, output, and polarity selection, the MCP23008 has numerous 8-bit Configuration registers. By writing the I/O Configuration bits, the system master can activate the I/Os as either inputs or outputs. The data for each input and output is stored in the Input and Output registers, respectively. The Polarity Inversion register inverts the polarity of the Input Port register. The system master has access to all registers.

The interrupt output can be set to activate on one of two (mutually exclusive) conditions:

1. This is used to notify to the system master that an input state has changed when any input state differs from its matching Input Port register state.

2. When the state of an input differs from the value of a pre-configured register (DEFVAL register).

The Interrupt Capture register saves the situation that produced the interrupt by capturing port values at the moment of the interrupt.

The  Power-on Reset  (POR) restores the default values of the registers and starts the device state machine.

The device address is determined using the hardware address pins.

Pinout

Symbol

Footprint

3D Model

• 8-Bit Remote Bidirectional I/O Port

- I/O pins default to input

• High-Speed I2C Interface

- 100 kHz

- 400 kHz

- 1.7 MHz

• Hardware Address Pins

- Three for the MCP23008 to allow up to eight devices on the bus

- Two for the MCP23S08 to allow up to four devices using the same Chip Select

• Configurable Interrupt Output Pin

- Configurable as active-high, active-low or open-drain

• Configurable Interrupt Source

- Interrupt-on-change from configured defaults or pin change

• Polarity Inversion Register to Configure the Polarity of the Input Port Data

• External Reset Input

• Low Standby Current: 1 µA (max.)

• Operating Voltage:

- 1.8V to 5.5V at -40°C to +85°C

I²C at 100 kHz

SPI at 5 MHz

- 2.7V to 5.5V at -40°C to +85°C

I²C at 400 kHz

SPI at 10 MHz

- 4.5V to 5.5V at -40°C to +125°C

I²C at 1.7 kHz

SPI at 10 MHz

Microchip Technology MCP23008-E/P technical specifications, attributes, parameters and parts with similar specifications to Microchip Technology MCP23008-E/P.

Functional Block Diagram

The project we'll talk about will show us how to connect an Arduino microcontroller to an MCP23008 I/O port expander.

First, we'll go over project components.

Component of Project

• These are the main components of the project.

• MCP23008 I/O Port Expander.

• A few 220Ω resistors.

• A few LEDs.

• Arduino microcontroller.

Let us now go over our projects in greater depth.

A 220 resistor and an LED are connected to each input and output pin in this circuit.

We wired +5V to Vdd and Vss to GND for the input supply.

Connect analog pin 5 of the  Arduino  to pin  1 of the MCP23008, which is SCL. This ensures that the Arduino and the I/O port expander chip are on the same clock.

After that, we connected SDA pin 2 of the MCP23008  to analog pin 4 of the Arduino. Data can be transferred between the Arduino and the  I/O port expander chip using this connection.

Because the interrupts pin isn't used in this project, leave it disconnected.

The RESET pin is not used; instead, it is connected to +5V. If you wish to use it, simply attach it to the Arduino's digital pin,  If you want to reset all of the outputs, set this pin to low in cade.

Following that, we'll ground address pins A0, A1, and A2. The address of these three pins becomes 000.

Let's look at the illustration for a better understanding.

Arduino Interfacing

Because this microcontroller supports both the I2C and SPI protocols, it is utilized in a variety of projects and devices that employ both.