Skip to main content

Irrduino: A Sprinkler System Built Using Arduino, Android, Google App Engine, Python, and Dart



Developers frequently ask me if Dart is ready for the real world. Well, of course, that depends on the application. Check out this short video in which Joe Fernandez and I not only show that Dart can be used in the real world, we also show that it can be used to take the tedium out of watering your lawn!



The Dart code for Lawnville was originally written in January of 2012, a mere three months after Dart was launched as a "technology preview". That was six months before Dart's M1 release, so it's been updated a few times along the way. However, the code really hasn't fundamentally changed that much since the beginning.

Perhaps the most interesting piece of code is the use of a Queue (from the dart:collection library) to schedule watering tasks. You can click on different parts of the lawn, and the droid will fly over and water each section for a short amount of time:
  _actionQueue = new Queue();
  ...
  _actionQueue.add({'action': 'water', 'zone': el.id});
  ...
  void _executeActionQueue() {
    if (_actionQueue.isEmpty) {
      _waitingForTimer = false;
      _idle();
    } else {
      var action = _actionQueue.removeFirst();
      _doAction(action);
      _waitingForTimer = true;
      new Timer(new Duration(milliseconds: TIMER_INTERVAL),
                _executeActionQueue);
    }
  }
A Timer and window.requestAnimationFrame are used to control animations:
  void _repositionDroid(int x, int y, [Callback callback = null]) {
    x -= (HALF * DROID_WIDTH).toInt();
    y -= DROID_HEIGHT;
    _droid.src = "/static/images/droid-jetpack-on-front.png";
    _droid.style.left = "${x}px";
    _droid.style.top = "${y}px";
    new Timer(new Duration(milliseconds: REPOSITION_DURATION), () {
      if (callback != null) {
        callback();
      } else {
        _droid.src = "/static/images/droid-waiting-front.png";
      }
    });
  }

  void _startAnimationLoop() {
    _animationStartTime = new DateTime.now().millisecondsSinceEpoch;
    window.requestAnimationFrame(_animationLoop);
  }

  void _animationLoop(int timestamp) {
    _animationProgress = timestamp - _animationStartTime;
    for (Callback callback in _animationCallbacks.values) {
      callback();
    }
    window.requestAnimationFrame(_animationLoop);
  }
An HttpRequest is used to send commands to IrrduinoServer which in turn sends commands to IrrduinoController in order to control the sprinkler system:
  void _waterRpc(int zone) {
    var req = new HttpRequest();
    int secs = (TIMER_INTERVAL * SECS_PER_MS).toInt();
    req.open("POST", "/?water-zone=true&zone=${zone}&secs=${secs}", true);
    req.onReadyStateChange.listen((Event e) {
      if (req.readyState == 4) {
        if (req.status == 200) {
          window.console.log("Watering was successful");
        } else {
          window.console.log("Watering was unsuccessful");
        }
      }
    });
    req.send();
  }
In total, the complete Dart code is about 110 lines long, not counting comments and closing braces.

You might wonder why I chose to use Dart so soon after its release, especially since I wasn't even on the Dart team at the time. I've always gotten a kick out of coding in new languages. At the time, I figured that as long as I could talk to the DOM and make XMLHttpRequests, I could do almost anything. These days, Dart is a lot more useful thanks to the growing selection of pub packages available, but even before these things existed, Dart had enough functionality to help water a lawn ;)

If you want to download the complete source code for Irrduino, you can get it from bit.ly/waterjoeslawn.

Popular posts from this blog

Dart in 2016: The fastest growing programming language at Google, 2nd fastest growing in TIOBE Index

Dart was the fastest growing programming language at Google in 2016 with millions of lines of code written. It also made it to TIOBE Index Top 20 this month (see TIOBE's methodology).

It takes time to build something as ambitious as Dart and, in some ways, Dart is still in its infancy. But we're glad the hard work is starting to pay off.

Many thanks to our amazing community!

We're going to celebrate by ... releasing 1.22 next week (as per our usual 6 week release schedule).

The new Google AdSense user interface: built with AngularDart

AdSense is a free, simple way to earn money by placing ads on your website. The team just launched a completely new version of their app for publishers. Read all about it here. We asked Daniel White, the tech lead for the project, some questions because the new UI happens to be built with Dart and Angular2.


AdSense launched way back in 2003. How long is it since the last big redesign?
Last big redesign was called ‘AdSense 3’ and launched about 6 years ago. It was written in Google Web Toolkit (GWT) and the UI has evolved through several iterations - but this is the first ground-up redesign in 6 years. There are a number of long-standing UX issues that we’ve taken the opportunity to solve. A big shout-out to our UX team who’ve been 100% behind this project. We couldn’t have done it without them!

How many software engineers worked on the project?
Purely on the AdSense applications, we have a team of close to 100. Around 25% of them write Dart.

How many lines of code?
We have around 160K LO…

AngularDart 2.1 and new Components

AngularDart got its own dedicated team 5 months ago. Last month, we launched 2.0 final on the Dart Developer Summit. Today, we’re releasing the first minor release after that: 2.1.

Since the focus of AngularDart is Productivity, Performance, Stability, there are no major breaking changes (see the changelog) — but a lot of behind-the-scenes improvements. Your apps will get slightly smaller and faster (even relative to 2.0 which already made huge strides in size and performance since the compiled-from-TypeScript days).

Many features that AngularJS had to implement for JavaScript and TypeScript are not needed in Dart (because Dart already has those features out-of-the-box). So we’re removing them from AngularDart. Renderer is deprecated in favor of plain-old dart:html. NgPlural is going away — Dart programs can use the package:intl library.

New components

On the Dart Developer Summit, we launched AngularDart Components — the material design widgets Google is using in customer-facing apps …