#include <Wire.h>

#define PB1 A0
#define PB2 A1
#define LED1 6
#define LED2 7

boolean systemOn = false;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(PB1, INPUT_PULLUP);
  pinMode(PB2, INPUT_PULLUP);
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  int stateButton1 = digitalRead(PB1);
  int stateButton2 = digitalRead(PB2);

  if (stateButton1 == LOW && stateButton2 == LOW) {
    systemOn = !systemOn;
    delay(500);
  }

  if (systemOn) {
    digitalWrite(LED2, HIGH);
    digitalWrite(LED1, LOW);
  } else {
    digitalWrite(LED1, HIGH);
    digitalWrite(LED2, LOW);
  }
}