How to turn on/off a led

Posted by mattia at 2011-03-25 13:34:58 UTC

This is the first milestone even if it can't be so tricky and unuseful but it's the concept behind all the process, so please pay attention, I get tons of emails with questions like:

• Which arduino should I buy?
• How can I generate the code for arduino?
• Why can't I sync my mobile with arduino?
• How should I configure my network?

in this tutorial we'are going to answer at those question starting from scratch.

Shopping list

• Arduino, I basically don't care which model of arduino you want to buy of you want to build your own on a cardboard, this does not metter we just need that the hardware is arduino complaiant. For all the people that haven't used arduino before I suggest to buy an Arduino Uno.
• Arduino ethernet shield, this is a mandatory brick because we are going to link it at our WiFi router through a RJ45 cable
• WiFi router, the brand it's not importnat, just a WiFi router, nowdays everybody has one at home
• One Led
• Some wires, if you don't have you can cut a RJ45 cable and use the wires inside

That's all.

We created DomoticHome web app to give at all the people that are not familiary with C/C++ an handly interface to generate the arduino code, in this way you just need to copy it and paste into the arduino IDE, compile and load into arduino. This is a pretty basic process so take a look here
http://www.arduino.cc/en/Guide/Environment
if you have any doubts.

So, register in DomoticHome and login on it, you should see some new voice into the menu bar:

• masters it is a simple hardware unit and it can be composed, for example, by an Arduino and an Ethernet shield. It takes care to communicate with the web application and the android device.
• devices it is whatever you want to link at your arduino, at this moment you can connect realys and integrated it with your home, for example, turn on/off light, open door and so on. But a device can be also a sensors, the data read from Arduino will be sent here too if you want and you can visualize graph of those reads.

Create Master

Before to start you have to know some parameters concerned your home network like:

• ip of your router
• subnet used (something like 255.255.255.0)

beacuse, as we told before, arduino need to communicate with your mobile and to  perform this it must to be connected at yout router, in this way you can handle arduino by your mobile via WiFi.

Click on "Master" and then "Create a new master" you'll see this screen

Fill up the following fields:

• name: label used for description ex: "my home"
• ip: arduino ip address, you have to insert a valid ip address for your subnet that it is not used by any other device (if it is not into the DCHP range it will be better)
• MAC: arduino MAC address, you can use this "0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xBE" but if you add a new arduino with ethernet shield on your home network you have to change this parameter because it is uniq for each device.
• subnet: your subnet
• gateway: your router ip
• port: use 80 and remember to set the same port on DomoticHome mobile app

Add Device

Click on the button "Add device", in this way we are going to add the support for our led and the system will generate the code for us. You should see a template like this

Name: this name will be show on our android device
Pin out: the arduino pin where the led will be linked
Device Type: select "light" so we will inform to show the "light" icon on the android device
Chibi Support: not used
Chibi address node: not used

Push the button "Create" and we will see a resume about the master and the devices created, as you can see there is link called "click to show the code", click on it and here is where the magic happens, copy the code, paste into the android IDE, compile and load on arduino.

Wiring

Now that the code has been loaded mount your ethernet shield on arduino and connect the led anod to the pin that you entred into the device configuration and katod  to ground.

After this connect arduino to your router via RJ45 cable.

Sync

STEP 1
Before to grab your android device we need to be sure that arduino is corretly linked to our router, so try to ping it. Open a shell and digit this:
ping yourarduinoip

if arduino correctly response at your ping go forward otherwise check your network configuration by pinging your router and control the arduino network configuration on master page by editing the ip,subnet and so on, reload the code on arduino and try again.

STEP 2
Open your browser and go to this url:
http://yourarduinoip/?out=all
you should see a JSON string as response like this:

{"ip" : "192.168.10.23", "devices" : [{ "type" : "light", "name" : "led", "out" : "5"}]}

it rapresents the list of devices configured on arduino, the same HTTP GET will be triggered during the sync process on your android device, after this the device will store the lists of devices and masters in its internale sqlite database.

STEP 3
Everything should be correctly configured so grab your android device set the correct ip in settings (menu->settings) page and then sync the device with arduino (menu->sync).
The device list will appear.

Jump into the detailed page

and there are 2 buttons, one for turn on the light and another one to turn off the light.
Done.