#include <Arduino.h>
#include <Adafruit_MCP23X17.h>

#define LED_PIN 0
#define BUTTON_PIN 1

Adafruit_MCP23X17 mcp;

// https://github.com/adafruit/Adafruit-MCP23017-Arduino-Library

void setup() {
    Serial.begin(9600);
    //while (!Serial);
    Serial.println("MCP23xxx Blink Test!");

    // uncomment appropriate mcp.begin
    if (!mcp.begin_I2C()) {
        //if (!mcp.begin_SPI(CS_PIN)) {
        Serial.println("Error.");
        while (1);
    }

    // configure pin for output
    mcp.pinMode(LED_PIN, OUTPUT);
    // configure pin for input with pull up
    mcp.pinMode(BUTTON_PIN, INPUT_PULLUP);

    Serial.println("Looping...");
}

void loop() {
    mcp.digitalWrite(LED_PIN, HIGH);
    delay(500);
    mcp.digitalWrite(LED_PIN, LOW);
    delay(500);

    // LOW = pressed, HIGH = not pressed
    if (!mcp.digitalRead(BUTTON_PIN)) {
        Serial.println("Button Pressed!");
        delay(250);
    }
}