Web Controlled Arduino LED

This instructable shows you how to build a Web-enabled tri-color LED based on an Arduino and the WIZnet Ethernet shield, controllable from any Web browser .

Check the live demo at http://try.yaler.net/~arduino/led

Because the LED is exposed through a simple RESTful web service running on the Arduino color changes can also be triggered by Pachube or other platforms offering Web hooks. Welcome to the Web of Things ! The LED can of course be replaced by a motor or a high voltage switching relay to enable more interesting browser controlled applications, e.g. for home automation.

Publishing your Arduino through the Yaler relay server makes the Arduino accessible from everywhere even if it is hidden behind a firewall or a NAT and does not have a public IP address. A single Yaler relay server instance can host many Arduinos (and any other device with a TCP Socket library, e.g. a Sheevaplug or an Android phone) and is available for non-commercial use including full source code at http://yaler.org/ (Disclosure: I founded the company developing Yaler)

Material

• Tri color LED [Ladyada | SparkFun]
• Arduino Duemilanove ATmega 328 [Ladyada | SparkFun]
• Arduino WIZnet Ethernet Shield [Ladyada | SparkFun]
• Resistors [1 x 150 Ohm, 2 x 82 Ohm for the Ladyada LED or
                      1 x 180 Ohm, 2 x 100 Ohm for the SparkFun LED]
• RJ45 cable

Tools

• Soldering iron
• Helping hands
• A / B USB cable

Infrastructure

• Internet access with DHCP, no public IP address needed for Arduino
• (Optional: PC or Cloud Server with a public IP address, to run Yaler)

Step 1 Soldering resistors and wire to the tri-color LED

(Note: All images show the Ladyada LED with the corresponding resistors and wire color)

• Shorten all except for the longest leg of the LED
• Solder the resistors to the LED legs as shown below
• Shorten the remaining long leg
• If you use the Ladyada LED, solder the red wire to it [as shown below]
• If you use the SparkFun LED, solder the black wire to it

Comments

[jaypozo]

Great project, but it doesn't seem to work for me. Everything compiles and I can connect to the Arduino and see the colour select page, but when I click one of the boxes, it doesn't change on the Arduino. Any ideas? I get this output when I hit the page:

n/led/ HTTP/1.1

And this when I click on the RED box:


n/led/led/ff0000 HTTP/1.1
Host: try.yaler.net

It looks like the "isPut" variable never gets set to "true" and so the pins never get set.

[tamberg]

Hi, from the output it seems the path is shorter than the code expects. Which URL are you using to access your Arduino? Kind regards, tamberg

[jaypozo]

This is the URL I'm using: http://try.yaler.net/gsiot-2fds-hkan/led/

[tamberg]

Ok. Does it work if you use http://try.yaler.net/gsiot-2fds-hkan/led instead (without the final slash)?

Regards,
tamberg

[crackHacker]

ok i can get it to compile and everything but my network keeps showing it as expired on the lease.

[tamberg]

Hi, according to this thread http://code.google.com/p/arduino/issues/detail?id=716 calling maintain() might help. Cheers, tamberg

[whanif]

I had a problem, when compiling the "HelloTriColorLedYalerService.pde" sketch, the result return with errors and the main error is "cannot declare parameter 'c' to be of abstract type 'client'" can i know why ? I've add the EthernetDHCP into libraries but still produce that error. TQ

[tamberg]

Whanif, thanks for trying the code. Which Arduino model and Arduino IDE version did you use? And which version of the libraries? It's been some time since I wrote this code. Cheers, tamberg

[whanif]

Thank you for the reply, I'm now using Arduino Uno Revision 2 and the IDE is version 1.0, for the libraries, it is Version 1.0b4. Thanks in advance...

[tamberg]

Ok. I don't have an Arduino Uno R2, but I can try to recompile the code with the new IDE and libraries this weekend. Sorry for the delay...

[whanif]

Ok, thank you for your help...

[tamberg]

Looks like the Arduino libraries changed significantly with v1.0, as far as Ethernet is concerned. Upgrading the code might take some time. As a quick fix you can try to use Arduino 0018 (if that works with the Uno).

[tamberg]

Just added a new version of the source code for Arduino 1.0. Please let me know if it works for you. Cheers, tamberg

[whanif]

I've patched my latest Arduino libraries to version 0018 and this error come up -->

sketch_jan30a:-1: error: variable or field 'receiveYalerResponse' declared void
sketch_jan30a:-1: error: 'Client' was not declared in this scope
sketch_jan30a:-1: error: variable or field 'sendPutResponse' declared void
sketch_jan30a:-1: error: 'Client' was not declared in this scope
sketch_jan30a:-1: error: variable or field 'sendGetResponse' declared void
sketch_jan30a:-1: error: 'Client' was not declared in this scope
sketch_jan30a:-1: error: variable or field 'receiveRequest' declared void
sketch_jan30a:-1: error: 'Client' was not declared in this scope
In file included from C:\Documents and Settings\User\Desktop\arduino-1.0\libraries\Ethernet/Ethernet.h:5,
from sketch_jan30a.cpp:29:
C:\Documents and Settings\User\Desktop\arduino-1.0\libraries\Ethernet/Client.h:17: error: conflicting return type specified for 'virtual void Client::write(uint8_t)'
C:\Documents and Settings\User\Desktop\arduino-1.0\hardware\arduino\cores\arduino/Print.h:48: error: overriding 'virtual size_t Print::write(uint8_t)'
C:\Documents and Settings\User\Desktop\arduino-1.0\libraries\Ethernet/Client.h:19: error: conflicting return type specified for 'virtual void Client::write(const uint8_t*, size_t)'
C:\Documents and Settings\User\Desktop\arduino-1.0\hardware\arduino\cores\arduino/Print.h:50: error: overriding 'virtual size_t Print::write(const uint8_t*, size_t)'
In file included from C:\Documents and Settings\User\Desktop\arduino-1.0\libraries\Ethernet/Ethernet.h:6,
from sketch_jan30a.cpp:29:
C:\Documents and Settings\User\Desktop\arduino-1.0\libraries\Ethernet/Server.h:20: error: conflicting return type specified for 'virtual void Server::write(uint8_t)'
C:\Documents and Settings\User\Desktop\arduino-1.0\hardware\arduino\cores\arduino/Print.h:48: error: overriding 'virtual size_t Print::write(uint8_t)'
C:\Documents and Settings\User\Desktop\arduino-1.0\libraries\Ethernet/Server.h:22: error: conflicting return type specified for 'virtual void Server::write(const uint8_t*, size_t)'
C:\Documents and Settings\User\Desktop\arduino-1.0\hardware\arduino\cores\arduino/Print.h:50: error: overriding 'virtual size_t Print::write(const uint8_t*, size_t)'
sketch_jan30a.cpp: In function 'void setup()':
sketch_jan30a:217: error: redefinition of 'void setup()'
sketch_jan30a:2: error: 'void setup()' previously defined here
sketch_jan30a.cpp: In function 'void loop()':
sketch_jan30a:230: error: redefinition of 'void loop()'
sketch_jan30a:7: error: 'void loop()' previously defined here


any ideas ?

[tamberg]

Assuming you are using the unchanged code from this Instructable it's hard to understand how those errors could result. Unfortunately my 0018 version of the IDE is broken in another way. I tried to verify the code on 0022 though, and there it works if you select the menu entry Include > SPI before verifying the code.

Sorry for the trouble,
tamberg

[cvasantrao]

Looks like try.yaler.net is down again. A very interesting project. Was planning something of the sort

[tamberg]

Cvasantrao, the relay try.yaler.net is up and running (http://status.yaler.net/), but it happens that the Arduino goes offline (the current code needs a reset from time to time) which results in a 504 Gateway Timeout. Some browsers display this as an empty page or even an error. Cheers, tamberg

[amcelmon]

I have a similar project i'm working on, an alert light based on values in a database. I originally started this project thinking I would be making outbound requests to a webserver, on a timer, from Arduino and switching lights based on the returned values.

Am I better off having having the webserver send simple requests to my Arduino device or the other way around.

[tamberg]

Hi amcelmon, interesting question. If you need real-time updates, the timer would probably be a bad idea, as the interval would have to be very low and thus a large number of requests (most of them in vain) would be sent from the Arduino. If a delayed update is fine, your solution would work and probably be simpler. But another question is how much of the logic you'd like to put on the Arduino. My example exposes just a very thin API layer above the hardware (i.e. the LED), which enables you to keep the application logic in the cloud (as a Web client) or even on your desktop (try cURL with my LED). This way (embedded device as a Web server) it's almost trivial to make mash-ups using different Web APIs. Cheers, tamberg

[tamberg]

PS. In your case you can further decide to couple your DB Web Server tightly with the Arduino (by calling out directly from the DB Web server to the Arduino Web server) or loosely (by having a scripted Web client call both your DB Web server and the Arduino LED Web server).

[jcouch1227]

Hi, if i wanted to run this same sort of operation over a local network, would an ethernet shield be necessary? I want to control my arduino with a website on an iphone but have no need to do it anywhere in the world :) thanks.

[tamberg]

Hi, the Ethernet shield is necessary if you want to host a Web page on your Arduino. The Yaler relay specific code is only needed if you want global access. Cheers, tamberg

[a_pineda]

I had problems with running my own instance and using the "HelloTriColorLedYalerService.pde" arduino code above. To get it to work properly, I had to modify the "parseYalerResponseChar" function as follows to get it to work:

// if (yalerCount == 56) { // sizeof("HTTP/1.1 101 ... \r\n\r\n") - 1
if (yalerCount == 75) { // sizeof("HTTP/1.1 101 ... \r\n\r\n") - 1

Now it works fine. Apparently the returned HTML is longer on the source code version that what comes back from Yaler.net.

Maybe I built the Java source incorrectly, but this fix seems to work for me.

[tamberg]

Thanks for the comment. You are right, the current hosted version differs from the open source version in this respect. Kind regards, tamberg

[tyao]

Hi, this is a very nice project. May I recommend that you put a income data filter to limit the light options to red, green, and blue. I am currently able to go into Firebug, edit the button commands to send whatever data I want. ie. I set the Green button to send "ffffff" which results a almost white led. OR "000000", which turns off the led. maybe "ff00ff" which would give purple.

overall, this project is very well designed

[tamberg]

Hi tyao,

thanks for checking out this project. You're right, it's currently possible to set other colors than red, green and blue. The LED has a public interface which let's you send HTTP requests to control it. In addition to editing the button command you can use cURL, the Poster Firefox plugin or any other Web client to send an HTTP PUT request "by hand". Of course you're also right that such an interface should only allow valid settings and filter the rest.

Cheers,
Thomas

[tedlawson]

Caught my errors ... working nicely. Onward!

[tamberg]

Hi Ted, good to hear it works. Thanks for investing your time in this. Cheers, tamberg

[tedlawson]

After initial success in duplicated this project, I've been getting the 504 error for the past week. I also tried it using a Mega

[tedlawson]

Basically duplicating what you have laid out in your instructions and with the addition of JTV. As I said, I had the basic version running fine. I then inserted the code for JTV and when I invoked try.yaler it came back with the 504 error,,, still does even when I go back to the version described here which was working last Sunday and hasn't since.
Can't get your link above to connect either.

[tamberg]

Hi Ted,

the memory on the Arduino is pretty terse. Depending on the size of your change, that might lead to the Arduino code not running at all.

The example above on the other hand, just needs a rest.

Cheers,
tamberg

[tedlawson]

Was up & running. Now seems I (or your demo) can't connect with Yaler. Is this service intermittent. Have JTV embedded nicely in my web site (tedlawson44.com/catcam/JTV.html), but haven't had a chance to see it in Yaler due to the (disconnect?)

[tamberg]

Hi Ted, could you please provide some more info about what you're trying to do? The Yaler instance http://try.yaler.net/ seems to be up and running. The Arduino might need a reset from time to time as the code is not completely stable over longer periods. Your page http://tedlawson44.com/catcam/JTV.html is accessible from my computer. Cheers, tamberg

[tamberg]

Hi, looks like http://try.yaler.net/ is down. Will investigate. Sorry for the inconvenience. Cheers, tamberg

[tamberg]

Ok, http://try.yaler.net/ should be up again.

Cheers,
tamberg

[tedlawson]

I miss your demo. Tried to get this going: substituted my MAC from the Ethernet shield and current IP of 'try.yaler.net" (46.137.106.125) and changed the generic ID. Uploaded OK but cannot connect?
In step 5 you state: "if the Yaler instance at the specified IP address is up and running". Don't really know what this means or how correct it?
Any insight?
Thanks

[arduino man]

This is a lot of fun!!!!

[tamberg]

Hi jcouch1227,

to serve a Web-page over a LAN the Ethernet Shield is still necessary. If the phone is connected via Wifi you might be able to access the site without a relay server or port forwarding. Otherwise, if the phone is connected to the Internet via mobile network, you'll need a public IP for your Web-server (or some sort of relay, as decribed here).

Cheers,
tamberg