var sonic = require('@amperka/ultrasonic') 
  .connect({trigPin: P10, echoPin: P11});
  
var buzzer = require('@amperka/buzzer') 
  .connect(P5)
  .frequency(50);
  
var light = require('@amperka/led') 
  .connect(P1);
  
var barrier = require('@amperka/servo') 
  .connect(P13)
  .write(90);
  
var hysteresis = require('@amperka/hysteresis') 
  .create({high: 0.5, highLag: 4, low: 0.5, lowLag: 0});
  
setInterval(function() { 
  sonic.ping(function(err, val) {
    if (err) return;
    hysteresis.push(val); 
  }, 'm');
}, 100);

hysteresis.on('low', function(val) { 
  buzzer.beep(1, 0.5); 
  light.blink(1, 0.5); 
  barrier.write(0);
});

hysteresis.on('high', function(val) { 
  buzzer.turnOff();
  light.turnOff();
  barrier.write(90);
});