Instructables
Picture of 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'm a founder of 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

Picture of Soldering resistors and wire to the tri-color LED
4343262388_316a9ca0b3.jpg
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(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

 
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egwillfriedel2 months ago

Works great!! best internet controled arduino tutorial I have seen thus far.

tamberg (author)  egwillfriedel2 months ago
Thanks!
nedhallett28 months ago

hi I was wondering if this tutorial is doable with an uno or leonardo board ?

Milen10 months ago
Hi, I am trying to reproduce the project using ARDUINO MEGA. I have created an yaler account and I am able to see the webpage with the 3 colored buttons. The problem is that nothing happens pressing the buttons. I added the following lines inside the code:

if (yalerState == YALER_UPGRADED) {
      //Serial.println("upgraded");
      receiveRequest(client);
      if (state == DONE) {
        if (isPut) {
        Serial.print("    led0="); 
        Serial.print(led[0]);
        Serial.print("    led1="); 
        Serial.print(led[1]);
        Serial.print("    led2="); 
        Serial.println(led[2]);       
         
          setColor(led[0], led[1], led[2]);
          sendPutResponse(client);
        } else {
          sendGetResponse(client);
        }
      }
    } else {
      //Serial.println("timeout");
    }

 I want to see what data is send to the PWM channels. The result from the Serial monitor is:

    led0=0    led1=0    led2=0
    led0=0    led1=0    led2=0
    led0=0    led1=0    led2=0
    led0=0    led1=0    led2=0
    led0=0    led1=0    led2=0
    led0=0    led1=0    led2=0
    led0=0    led1=0    led2=0
    led0=0    led1=0    led2=0
    led0=0    led1=0    led2=0


 That means - pressing the buttons does not effect the values for the LED intensity. Please suggest where the problem could be...
tamberg (author)  Milen10 months ago
Hi, the parsing of the incoming HTTP request in this example is not very robust. There might be a broken offset or something similar in receiveRequest. Unfortunately I don't have an Arduino at hand to test anything before mid January. Regards, Thomas
btan31 year ago
Hi,

I made changes to the code and everything. Now I'm trying to access the website but I can't. I tried http://46.137.106.125/{Relay Domain}/led and http://try.yaler.net/{Relay Domain}/led. Both of the lead to server error page. Am I missing something here?
tamberg (author)  btan31 year ago
Hi,

the server error page is likely HTTP Status 504 (Gateway Timeout). This is Yaler's response if no device is available at the given Relay Domain.

Reasons might vary from typos to memory overflow. Can you add some Serial output to your Arduino program to see if the program is running and if it get's the request from your browser?

Kind regards,
Thomas
btan3 tamberg1 year ago
Hi,

Thanks for the reply. I uncommented all serial print commands in the code. It prints setup on the serial monitor which means it goes through void setup but nothing after that and I can't access the website. Am I using the correct web address here? I'm using arduino nano with ethernet shield btw if that makes any difference.

Thank you.
tamberg (author)  btan31 year ago
If the shield works fine with other examples, maybe the Nano runs out of memory?
btan31 year ago
Hi,

When you say "you should now be able to access the Arduino Web LED at http://{Yaler IP}/{Relay Domain}/led", what is the Yaler IP?
tamberg (author)  btan31 year ago
Hi, if you use the hosted ervice the IP in the source code is fine.

Kind regards,
Thomas
bajonjon1 year ago
hello sir,.can you upload the complete code???
tamberg (author)  bajonjon1 year ago
Just sent you a message. Regards, Thomas
renexdon1 year ago
Hi tamberg, firstly congratz for this very useful post. I'm quite new with Arduino and Web of the Things staff, I'd like to implement the java apps directly on my google app engine account, I use Eclipse for that purpose, any suggestion? ReneX
tamberg (author)  renexdon1 year ago
He renexdon, Sounds great. Your Java App could call the Arduino via HTTP. Regards, Thomas
Are you planning to get your demo working again? I enjoy playing with it, it is my homepage
tamberg (author)  Michael_Bell1 year ago
Glad you like it. Sometimes it's stuck and needs a reset. Will do that ASAP.
jaypozo2 years ago
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 (author)  jaypozo2 years ago
jaypozo, the code didn't work anymore due to a change on the relay. Please download the updated version from this Instructable. Regards, tamberg
tamberg (author)  jaypozo2 years ago
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 tamberg2 years ago
This is the URL I'm using: http://try.yaler.net/gsiot-2fds-hkan/led/
tamberg (author)  jaypozo2 years ago
Ok. Does it work if you use http://try.yaler.net/gsiot-2fds-hkan/led instead (without the final slash)?

Regards,
tamberg
tamberg (author) 2 years ago
Just updated the ZIP downloads to reflect the new relay IP address and fix a parsing error.
crackHacker2 years ago
ok i can get it to compile and everything but my network keeps showing it as expired on the lease.
tamberg (author)  crackHacker2 years ago
Hi, according to this thread http://code.google.com/p/arduino/issues/detail?id=716 calling maintain() might help. Cheers, tamberg
whanif2 years ago
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 (author)  whanif2 years ago
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 tamberg2 years ago
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 (author)  whanif2 years ago
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 tamberg2 years ago
Ok, thank you for your help...
tamberg (author)  whanif2 years ago
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 (author)  tamberg2 years ago
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 tamberg2 years ago
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 (author)  whanif2 years ago
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
cvasantrao2 years ago
Looks like try.yaler.net is down again. A very interesting project. Was planning something of the sort
tamberg (author)  cvasantrao2 years ago
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
amcelmon2 years ago
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 (author)  amcelmon2 years ago
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 (author)  tamberg2 years ago
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).
jcouch12273 years ago
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.
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