Dallan’s weblog

Here are some scans from my current sketchbook. I hope you enjoy.

I have been working on a little project that ‘pushes’ Arduino data from a USB connected PC to a server running Red5. Red5 treats each Arduino pin as a shared object. So when a pin (the Arduino has 6 analog pins and 14 digital pins) updates, every visitor viewing a subscribing webpage gets live data. I wanted to see how fast I could publish sensor data using Red5. I’m also interested in the performance with regards to bandwidth usages (to/from the server), speed of updates, CPU usage on the client to display the rapidly updating data in the browser, etc…

Click Here to Start Streaming Live Arduino Data
Analog Pin0: n/a
Analog Pin1: n/a
Analog Pin2: n/a
Analog Pin3: n/a
Analog Pin4: n/a
Analog Pin5: n/a

how it works:

First the server side stuff –  I wrote a .NET DLL so I can communicate easily with the Arduino using .NET. Next, I created a simple .NET winforms app that includes my DLL. I will use this application to get the data from the Arduino. The Arduino itself is running Standard Firmata V1.0 (http://firmata.org/wiki/Download). A Flex/Flash Actionscript 3 swf is used to connect to Red5 and create a shared object for each each Arduino pins (i.e. AnalogPin0, AnalogPin1, …, DigitalPin0, …, DigitalPin13). This Flex swf is embedded into the .NET (C# in this case) WinForm (using ActiveX or OLE or whatever) and the ExternalInterface is used to pass messages from C# to Actionscript running in the swf. When the .NET app gets data from the Arduino, it passes it immediately to the swf. The swf is connected to the remote Red5 server and updates the appropriate shared object (pin) immediately. I’ve attached a couple of images of my setup (I’m using a ASUS eee box as my control PC (little black box with the blue LED). Ignore the TED display box for now, I’ll post about that later.

(continue reading…)

Pencil sketch scanned on 5-28-2009

I scanned in my latest sketch. This one has been a fun one to work on. There is still a lot of detail to add in the middle. I’ll scan it again as it progresses.

Sketch 1

Here’s a scan of page 1 of my most recent sketchbook. If you’re interested in seeing more scans, you can follow this link. I’m working on developing a new 3D Flash photo gallery that I’ll use to display all of these in the future. Stay tuned.

I’ve been playing around with this concept of sharing mouse movements and clicks with all users who are view the same webpage. So far, I have a rough prototype functioning (on this website and on www.porterdigital.com). Assuming you have a recent Flash player installed and your firewall allows RTMP socket connections, this should work for you. Try clicking around on this page (not on a link yet) and you should see your click. If anyone else is viewing this page right now, they’ll see it too. Try opening up a second browser window with this same URL and view them side-by-side. You should see your clicks and mouse moving around the page.

So here’s how it works: There is a tiny flash movie embedded into this page and it’s moved off screen so it doesn’t interfere with the page layout. This movie clip opens a persistent NetworkConnection (a RTMP socket connection) to a Red5 server (running on my office desktop). JavaScript listens for your mouse to move or a click to happen and relays this event to the Flash movie. Flash then sends that data off to the server. The server (running Red5) figures out who’s viewing this same page and pushes an event to that client immediately. The Flash movie receives the event and relays that event to JavaScript. JavaScript then moves the little cursors around or plays the animated ‘click’ thingy.

A custom Red5 application has been created to keep track of who’s visiting what page and which clients needs to be notified of which mouse events. Basically it’s a proxy for mouse events.

Granted, it’s a pretty cheesy example of using this technology, but I think the overall concept has some potential. It allows true ‘push’ to clients unlike AJAX which relies on polling. Let me know what you think.