#include <Wire.h>
#include "Adafruit_MCP23017.h"

Adafruit_MCP23017 Expander1; 

void setup() 
{  
  Expander1.begin(1); 
  for(int i=0 ; i < 16 ; i++)
  {
    Expander1.pinMode(i, OUTPUT);
    Expander1.digitalWrite(i, LOW);
  }
}
void loop() 
{
  for(int i=0 ; i < 16 ; i++)
  {
    Expander1.digitalWrite(i,HIGH);
    delay(80);
    Expander1.digitalWrite(i,LOW);
    delay(80);
  }
}