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

Adafruit_MCP23017 mcp;

int value = 0;
int total = 0;

void setup() {
  mcp.begin(0,D2,D1);

  for (int a = 0 ; a <= 15; a++) {
  mcp.pinMode(a, INPUT);
  mcp.pullUp(a, LOW);  // 100K pullup internally <- I tried commenting it out and changing it to HIGH
  }

}

void loop() {
  total = 0;
  for (int a = 0 ; a <= 15; a++) {
    value =  mcp.digitalRead(a);
    Serial.print(value);
    total += value;
  }
  Serial.println();
  Serial.println(total);
  delay(200);
}