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Topics: Autism Development

Accessing Xbox controller events in Node.JS on a Raspberry Pi

For a recent side project I needed access to events from an Xbox controller plugged into a Raspberry Pi via node.js.

For Mac I had been using the brilliant node-xbox-controller module. It had worked well, but after many hours of fighting I could not get it to work on the debain based Raspbian operating system. In the end I narrowed the problem down to something not working in the hidapi layer or below.

In order to receive the events I instead used a userspace driver called xboxdrv coupled with the node-joystick module.

This results in raw joystick events being passed into node.js. Each event has a value, a type (number or axis) and a number.

From there, I mapped each button from the raw events, into handy names using a nested structure:

var type = {
  button: {
    0: { 1: "a:press", 0: "a:up" },
    1: { 1: "b:press", 0: "b:up" },
    2: { 1: "x:press", 0: "x:up" },
    3: { 1: "y:press", 0: "y:up" },
    5: { 1: "rb:press", 0: "rb:up" },
    4: { 1: "lb:press", 0: "lb:up" },
    8: { 1: "xbox:press", 0: "xbox:up" },
    6: { 1: "back:press", 0: "back:up" },
    7: { 1: "start:press", 0: "start:up" }
  },
  axis: {
    7: { 32767: "ddown:press", '-32767': "dup:press" },
    6: { 32767: "dright:press", '-32767': "dleft:press" }
  }
}

The map is accessed as a big flat array:

var eventIsMapped = function(event){
  if (!event.init 
       && type[event.type] 
       && type[event.type][event.number] 
       && type[event.type][event.number][event.value]
  ) {
    return type[event.type][event.number][event.value];
  } else {
    return false;
  }
}

This can then be used to drive further code from a single interface.

joystick.on('button', function(event) {
  var action = eventIsMapped(event)
  console.log(actions[action]());
});

And there we go! From there I have a separate map to go from controller buttons to actions on the hue lights. The code in use can be found on my github account

Published: 14 September 2014 | Categories: , Permalink

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