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Simple and intuitive web interface for your Raspberry Pi

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The Raspberry Pi is an amazing 35 dollars mini-computer. It allows you to do everything you could do with a regular Linux computer (Connecting to the internet, watching videos, launching applications, ...) but also to interact with the world surrounding it, just like an Arduino. That's why I qualify it as a mix between a computer and a micro-controller.
That's also why I chose it for this project. I'm going to show you how to control LEDs with your Raspberry Pi. Firstly directly from the Raspberry Pi itself, then from any device in your house like your Smartphone or your tablet.

Here is a very good example of what you can achieve after reading this Instructable: http://www.instructables.com/id/Web-Controlled-8-Channel-Powerstrip/. Thanks to Rleddington for his amazing project.

Update: French version here

 
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Step 1: The electronic part

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     The electronic part is nothing special, it's only 8 LEDs with their protecting resistor. The only hard part is to connect the LEDs to the good pin on the Raspberry Pi. Indeed, I'll be using later a library called Wiring Pi made by Gordon Henderson (You can visit his website at: http://wiringpi.com/) and the pin's numbers used in this library aren't the same than the ones on the Raspberry Pi. See this page for matches: http://wiringpi.com/pins/ (just be careful about your Raspberry Pi revision, the pinout isn't exactly the same). I'll be using Wiring pins 0 to 7.
     Concerning the resistors, they should be 270Ω but since I don't have this precise value, I'm using 560Ω resistors (LEDs are just less bright).
     Finally, I've made two schematics to make it simpler. The first one (with the complete Raspberry Pi) is showing you the real pins as they are shown on the board. The second one is a simplified version, it's showing you only the useful pins and their matches in the Wiring Pi library (GPIO Wiring number/Actual number on the board).

Step 2: Installing and using the Wiring Pi library

     As said before, Wiring Pi is a library. It simplifies a lot using the Raspberry Pi GPIOs (one command instead a long process). It also means that you can use it in any of your C codes. However, we won't build and use a C program but the Gpio utility. It's a software made by Gordon and coming with the library. It allows you to control the GPIOs in a bash script or directly in a command line. Using this utility is however a lot slower than a C program.

     We first need to install it. Gordon himself is explaining it very well on his website: http://wiringpi.com/download-and-install/. You just need to download it from GIT then to build it using the ./build command.
     You should now be able to use the Gpio utility, type the "gpio mode 0 out" command to test it out. If nothing special appears, everything's fine. Else, if the board is printing "command not found error" or something like that, be sure that you've followed the guide and build the library.

     Let's turn on and off the first LED (Wiring pin 0). You first need to set the pin as an output. Use the "gpio mode 0 out" command to do so. "0" is the wiring pin number and "out" simply stands for output. Now, use the "gpio write 0 1" command to turn on your LED. "0" is again the pin number and "1" is the status (1 for ON and 0 for OFF). If everything's fine you should see your LED shining. To turn it off, simply use the "gpio write 0 0" command.
     Just a little tip, if you want to use the actual pin number (GPIO-17) instead of the Wiring Pi number (0 is corresponding to GPIO-17), use the -g flag in your command. Ex: "gpio -g write 17 1" instead of "gpio write 0 1".

      There is also the "gpio read" command which allows you to read the pin's status. It may seems useless when the pin has been set as an output but it allows you to be sure of the pin's status when you can't see the LED. Using it is as simple as before, just type "gpio read 0" where "0" is the wiring pin number. The command is returning the pin's status (again 1 for ON and 0 for OFF).

     Finally the Wiring Pi library is containing a lot of other commands/functions but I'm not gonna cover them in this instructable since there are not useful here. See this page if you are more curious: http://wiringpi.com/reference/ (library's functions) and https://projects.drogon.net/raspberry-pi/wiringpi/the-gpio-utility/ or the "man gpio" command for the Gpio utility.

     Now that you can use this utility, let's play a little bit with it. You can first, if it's not already the case, control remotely your Raspberry Pi with SSH. You can use Putty for Windows or ServerAuditor for your Smartphone. Then have fun with bash scripts such as this one which is turning on LEDs 0 to 7, waiting 2 seconds, then turning them off again:
 
#!/bin/bash

#set mode to output
for i in 0 1 2 3 4 5 6 7;
   do gpio mode $i out;
done;

#turn on LEDs 0 to 7
for i in 0 1 2 3 4 5 6 7;
    do gpio write $i 1;
done;

#wait 2 seconds
sleep 2;

#turn LEDs off
for i in 0 1 2 3 4 5 6 7;
    do gpio write $i 0;
done;

Step 3: Installing a web server then transferring your website to it

Picture of Installing a web server then transferring your website to it
     Controlling the LEDs remotely with SSH is pretty cool but the interface (console) isn't very user friendly and typing the commands every time is long and annoying. That's why we need a graphical interface for our project.
     Programming an app for each OS (IOS, Android, Windows phone, Mac, Linux, Windows,...) would be too long and would require to know a lot of different languages for nearly nothing. It would also require to do an application running on the Raspberry Pi. Making it this way would be overkill and time wasting.
     That's why a website is the best solution, it's compatible with all devices and you "only" need to know four languages: HTML (for the page's skeleton), CSS (page's style), PHP (interactions with the server) and JavaScript (interactions with the user).

     We indeed need to install a web server on the Raspberry Pi. In our case, we don't need a MySQL database, only a HTTP server and its PHP extension.
     After updating your Raspberry Pi with the "sudo apt-get update" command, type "sudo apt-get install apache2 php5 libapache2-mod-php5" to install Apache HTTP server and PHP5 extension. You can now test if your server is working by typing the IP of your Raspberry Pi in your browser. You should now see a "It works!" page with two other lines. If you don't, then check your board's IP, try re-installing Apache or rebooting your Raspberry Pi. This page is showing that your Apache server is working properly but not its PHP extension. To check it, navigate to your "/var/www/" directory by using the "cd /var/www/" command. If you use the "ls" command, you should have only one file named "index.html". This file corresponds to the "It works!" page. You can now delete it ("sudo rm index.html") and create another one called "index.php" (use "sudo nano index.php"). Then type the following text:
 
<?php
     phpinfo();

?>

     After saving it using ^o (Ctrl + o), exit nano editor with ^x (Ctrl + x). Now if you refresh your browser, you should see a long page with lots of information about your server and PHP. If you don't, check the index.php file, try re-installing PHP or try to understand the error displayed instead of the page (Google it if necessary).

      If both pages were correctly displayed, then you now have a fully functional Apache/PHP server but using nano every time is annoying and not very comfortable. We indeed need to transfer files from your computer to your Raspberry Pi. You may want to install a FTP server but it isn't necessary, you can already transfer files using the SFTP protocol. All you need is an SFTP client on your computer. I'm personally using  WinSCP for Windows but there are Cyberduck for mac and Filezilla for Linux. If you try transferring files before reading what's next, you'll probably have issues such as "access refused" or "cannot write here". It's due to the fact that the user pi isn't owning the www directory. Indeed, if you try the "ls -l /var/www" command, you'll see that only root (the super user) is owning the www directory. You can (like I did) use the "sudo chown -R pi /var/www" command to change it or create a group named www-data in which you place the pi user then use the "sudo chown -R www-data /var/www" command. The -R flag is standing for recursive, it means that the user/group isn't owning only the directory itself but also everything inside (index.php as example).
     You now have your server ready to work and to receive web pages. Have fun with it if know HTML, CSS and PHP.

Step 4: Controlling the LEDs with PHP

Picture of Controlling the LEDs with PHP

We now have a web server and a library, let' put them together.
PHP stands for "PHP: Hypertext Preprocessor", It's a server side scripting language. It means that the PHP code is executed once (each time the page is requested) by the server and cannot be seen by the client. I used this language because it's the most popular (and that's the only one I know) but you have to know that they are other server side languages like Python, Ruby, Lua, Perl, ... However, I don't know if the functions we are gonna use have their equivalents in these languages.

Executing applications with a PHP code can be done with two different functions: exec (for execute) and system. Firstly, the "system" function. It takes two parameters: "system ( string $command, int $return_var )", as you guessed it, the first parameter is the command to execute and the second one is the returned status of the executed command. The second parameter isn't compulsory. You can use this function if you don't expect an answer from the command executed. Thus, you can use it if you need to execute "gpio mode 0 out" or "gpio write 0 1" commands. Example:

<?php
     system ( "gpio mode 0 out" );
     system ( "gpio write 0 1" );
?>

Then, the "exec" function. This function is making exactly the same work than "system" but it reads and stores what the command printed. It takes three parameters: "exec ( string $command, array $output, int $return_var )", again $command and $return_var are the same parameters and the only difference is the $output array. As it's name says it will store the command's output in an array. Thus, you can use this function if you need what the command prints like with the "gpio read 0" command. Example:

<?php
     exec ( "gpio read 0", $status );
     print_r ( $status );
?>

You can now execute nearly whatever command you want but let's make a little PHP example to practice: We will turn on LEDs 0 to 7, then wait 2 seconds, then turn them off. Just like we did with the bash script. Edit the index.php file with the following code:

<?php
$status = array ( 0 );
//set pins mode to output
for ($i = 0; $i <= 7; $i++ ) {
     system ( "gpio mode ".$i." out" );
}
//turns on the LEDs
for ($i = 0; $i <= 7; $i++ ) {
     system ( "gpio write ".$i." 1" );
}
//reads and prints the LEDs status
for ($i = 0; $i <= 7; $i++ ) {
     exec ( "gpio read ".$i, $status );
     echo ( $status[0] );
}
//waits 2 seconds
sleep ( 2 );
//turns off the LEDs
for ($i = 0; $i <= 7; $i++ ) {
     system ( "gpio write ".$i." 0" );
}
?>


Step 5: Making the interface

We can now control our Raspberry Pi with simple PHP scripts but there is no interaction with the user and thereby we can't choose the LED to turn on/off. Let's make the interface!
It's composed of pictures I've found on Google images (search for "on/off button"). One was green and the other one red, I just added the number using The Gimp. Each picture/button is corresponding to its LED, so if you click on one of these, the corresponding LED will be turned on/off and the picture will be changed to its green/red version. The page's skeleton will be made with HTML, the server interactions and page's generation with PHP and at last JavaScript to manage interactions with the user and page's animation. If you don't know, JavaScript is a client side language and unlike PHP, it's executed not once, but continuously by your browser. That's why you can change the page's look without reloading it or accessing to an other. If you are wondering why I spoke about CSS before, it's just because we need it for some style and page-layout like the the black background. I didn't make a full .css file because it wasn't necessary here.
We first need an "index.php" file (extension is .php and not .html cause we will use PHP code, it helps the server to know if there is PHP to execute before sending the generated page). This page is the main page containing the 8 buttons. These buttons are first generated with a "exec ( "gpio read ".$i, $output );" in a for loop. Then we need to detect when the user is clicking on one of these buttons. That's where the JavaScript is useful, I put it in a separate file called "script.js" but it's still included in index.php. The script is simply adding an event listener to all of the eight buttons and each time one of these is pressed, it uses a function which is asking for gpio.php, receiving the answer then returning it. Finally, in function of this, the JavaScript changes the button to red (for OFF) or to green (for ON). Now, the last page: gpio.php. It contains the PHP code to turn on/off the LEDs in function of what the JavaScript function sent. The user shouldn't normally ask for this precise page but there is one golden rule when creating websites and you should always remember this one: "NEVER TRUST THE USER". In other words, never think the user is always gonna do what you think he's gonna do. Thus, I added some securities at the begin of the PHP code like making sure the user gave a correct value and not a letter as example. I made a small diagram to sum up all this text.

You can download the full project directly on this website below.

Web.zip701 KB

Step 6: Conclusion and ideas of improvements

This small but long explained project was fun and I learned a lot. I hope you did the same. However, controlling LEDs isn't very useful. That's why what we made is rather a tool than a real project. Christmas is soon (about one and a half months from the day I wrote this instructable) so why not replacing LEDs by relays and controlling lights around your house. There are some pretty good relay boards for the Raspberry Pi on Ebay and more generally on the Internet. Alternatively, and if you're not scared about working on your house, you can even control your house's lights, garage door, coffee machine, heating system, ... The only limit is your imagination.
There are also a lot of possible improvements like changing the interface, adding more LEDs via a shift register, using vocal recognition, ... In addition, with PHP, you are not limited to gpio write or read. You can use the full Gpio utility and thus interact with other devices with UART or any other implemented protocol. You can also use PWM (Pulse Width Modification) to control servos, ...
Writing this Instructable and sharing my little knowledge was a great pleasure for me and I hope it was the same for you to read it. I tried to keep it simple but at the same time to teach the most possible. I didn't want to do a simple and dumb step by step: "download this code, run it, you're done". I think that something is useless to learn until you understand how it works or why you do this and not that. Let me know if you think it's the good way or if I should do it otherwise.

PS: This is my very first instructable and English is not my native language so if you have any comment, advice, suggestion, idea, ... Just let me know, I'll be glad to answer you and of course to learn.

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rustic99 made it!6 days ago

TheFreeElectron,

Thank you for the brilliant tutorial! I'm having a bit of trouble changing what GPIO pin is used for button 0 (because I think I shorted out GPIO17 and damaged the Pi). In your diagram you define GPIO17 for button 0 but I cannot find this anywhere in your code. Where in the code can I change what GPIO pin is used? Other than that this was a fantastic tutorial!

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TheFreeElectron (author)  rustic996 days ago
Thank you! Your installation looks really nice!

Actually, I haven't defined anything, I just have 8 buttons (from 0 to 7) corresponding to Wiring Pi pins 0 to 7, the only link is the one defined by Gordon when he made the library and soft (see the link provided in one of the step). If you want to change a pin, you'll have to do it in the JS I think, instead of calling the "change_pin" function with parameters (0,1), do it with (8,1) where 8 is corresponding to the pin you wanna use.

Hope I Helped,
TheFreeElectron
rustic997 days ago

Red/green on and off buttons for everyone to use!

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TheFreeElectron (author)  rustic996 days ago
Nice work! Thank you!
fedexxx18 days ago

You have a java script (for php) for check the status of pin in real time?

fedexxx19 days ago

hi,

if i compile a file .c and i run on php ( system("./path"); ) it's not work!

I try whitc blink.c

TheFreeElectron (author)  fedexxx19 days ago
Hi!

I already tried such a thing, If I remember well, I had to place the compiled file into a special directory, so Linux recognized it as an application I could use by typing its name. This way, I had no trouble executing the compiled C code with a PHP script. Search for something like "creating linux commands".

Hope I Helped,
TheFreeElectron

I think that the error is on "wiringPI" because if executive the "blink" on Guest ( no root - no sudo) i have:

pi@raspberrypi / $ blink

wiringPiSetup: Must be root. (Did you forget sudo?)

Sorry for my english

TheFreeElectron (author)  fedexxx18 days ago

yeah that's right, you must be root when using the wiringpi lib in a C code (sse the reference for more info). So you cannot use it via PHP (or you find a tricky solution on the internet). I was executing batch scripts using the software provided by Gordon, so no need for sudo.

AnfalA11 days ago

you use the LED and some resistors and what else the tools you used for this project ?

TheFreeElectron (author)  AnfalA10 days ago
none, only a few wires and a breadboard.
AnfalA12 days ago

hi

please can you give me the tools for this project?

because i won't to make it .

thank you !

TheFreeElectron (author)  AnfalA11 days ago
Hi!

All the software and hardware required for this project are shown in this 'Ible. I don't really understand your request.

Hi,

Very informative tutorial. But how am i suppose to operate this from anywhere in the world??

Thanks in advance

Hi!

You'll need to open your router's port to allow incoming external connections. There are many tutorials on it, just google "access wamp server from outside" or something like this.

Hope I Helped,
TheFreeElectron
I have relay. And when i connect relay to pi it turn all relay lights on. 1. time with relay so i do not know is that normal. When i turn off light in the room connected to relay it light on a litle diode on the relay. When turn on .. than ,on the relay diode is off.( I think that should be reverse . When red picture is displayed than ralay or diode light on should be off.) If that is true. Can you tell me how to reverse all picture. Red to be green . Or how to change state on whole php and java from 0 when is off to 1 to be off and 0 to be on. ... it is hard to explain , sorry for long explanation. Maybe i should say how to reverse 0 and 1 state .
TheFreeElectron (author)  gago.babic.322 days ago

Hi!
If your problem is only that on and off status are reversed, simply reverse the green and red pictures in the index.php and script.js or by renaming the pictures directly (this method being a bit long and messy).

Hope I Helped,
TheFreeElectron

well. that helped. but , every time when site loads I have to click 2 times to turn on. and when turned on ,, if I reload page everything is fine but again I have to click 2 times. but thats fine. at least i got feedback of lights .. if they are turned on or off.

TheFreeElectron (author)  gago.babic.320 days ago

That's a kinda weird issue, try your browser's developer's mode/tool to observe the requests your browser is sending to the server so you can see if the request is sent twice or only once. This way, you'll understand better what is going on and what is changing and where.

browser is sending requests . i have replaced in index.php (

src='data/img/red/red_".$i.".jpg' alt='off'/>"); ) for (

src='data/img/green/green_".$i.".jpg' alt='on'/>"); ) and other vay around ..and in script.js i changed -

//if red
if ( button_0.alt === "off" ) {
//use the function
var new_status = change_pin ( 0, 0);
if (new_status !== "fail") {
button_0.alt = "on"
button_0.src = "data/img/green/green_0.jpg";
return 0;

from data/img/green/green_0.jpg TO data/img/red/red_0.jpg ...

And in whole butons I have changed from red to green and from green to red. so i think that first request from browser cant be correct. so something need to change in code. but i do not know what.

i get from developer s mode . only text replay when first click is presed. then second he is changing picture. i get this after first click.

gpio.php?pin=0&status=0

TheFreeElectron (author)  gago.babic.320 days ago

Well, that's kinda hard for me to understand what's happening. I understood that you've reversed red and green (which is basically just a visual trick) but I don't see why there would be the need to click twice for a status change to be effective. Maybe that you made, somewhere, a change in the code that compromised its logic and provoked this situation.
Try to ask someone, a programmer friend... if he can help you. That's all I can say thousands miles away with the information you gave me. ;)

satish.ip made it!20 days ago

TheFreeElectron,

Thanks for a wonderful tutorial! I tweaked few things to get the scripts working with Python GPIO control and integrated with your Php/Javascripts. And also added weaved IOT service on the Pi (they have a iOS app too), now I can control the devices being anywhere in the world!

Rpi_with_Relay_WebControl.JPG
TheFreeElectron (author)  satish.ip20 days ago
Thank you!
What you've done looks absolutely awesome!
SamK421 days ago

I followed all the steps but when I try and run the webpage on my computer it appears as a blank white page

Help would be appreshiated as I plan to make a robot that would be controlled using a php webpage

TheFreeElectron (author)  SamK421 days ago

Hi!
Did you checked if your server and the php extension are correctly working? (with the code in the step talking about the php.)
If you did and there was no problem at that time, make sure the files have been placed in the www folder. If yes, try other tests to find where the failure is. The goal is to test each component of the project one after the other to find where the issue is and to correct it, that's all I can say in front of my computer. ;)

Hope I Helped,
TheFreeElectron

milit.mitra21 days ago

Hi,

I tried placing the files (index.php, gpio.php javascript.js) in the www directory but could not using WinSCP. Could you please tell me how to access the www directory using WinSCP or should I be coding the files. I'm not so fond of coding but I want to complete this super interesting experiment as it fascinates me.

Hoping a reply.

TheFreeElectron (author)  milit.mitra21 days ago
Hi!

What do you mean by "could not using WinSCP"?
If your problem is finding the directory, its absolute path is "var\www".
If your problem are access rights, make sure your "user" (pi by default) is correctly owning the dir and its sub dir.

Hope I Helped,
TheFreeElectron
minagabriel22 days ago

You have an infinite loop

TheFreeElectron (author)  minagabriel22 days ago

Thanks, I've corrected, looks like the "++" have disappeared for no reason.

Hello again, i have been having lots of fun with this project and has been great fun in doing so. Im just hoping youd be able to help, i have the code below but wont to be able to create a master on and off button. but i can only get it to turn one pin on/off at a time. Does anybody know how to get to to do multiple pins at once??

--------------------------------------------------------------------------------------------

button_8.addEventListener("click", function () {

//if green

if ( button_8.alt === "on" ) {

//use the function

var new_status = change_pin ( 0, 1);

if (new_status !== "fail") {

button_8.src = "data/off-button.png";

return 0;

}}} );

Hi!
As said in one of my previous comment, you have two possibilities:
+You add a new function to gpio.php which turns all leds on or off and ask for that function in the JS code (the best and cleanest option to me)
+You add a kind of loop to the JS script using n times the change_pin function (slow and not sure this will work correctly because of doing having multiple request in a small amount of time)

Hope I Helped,
TheFreeElectron
mikerosati29 days ago

Wonderful first Instructable in English my friend :) I will be trying these steps out later today on a brand new pi B+...

TheFreeElectron (author)  mikerosati29 days ago
Thank you so much! That'll always be a pleasure! ;)

Hello, i have managed to get all of your code working, but i cannot figure out what pins i should be connecting to. I have the Raspberry PI Model B, & i think its the rev 1. Could you help please as im getting confused as an image i found said gpio 27 but i cannot find that gpio and only have 26 pins.

Also ever since i have restarted my pi i cannot access the index.php page from my browser via the ip address, do i have to manually start the service again or can i set it to start automaticaly?

Thank You

Hi!
Links between pin's number and name are quiet confused. See this http://wiringpi.com/pins/ page where everything is shown. Also you can easily choose and control other pins. The pinout is in one of the steps.
Try to see if the apache service is running (google it to find the command), if not start it again and see if it can be ran at every start-up, if yes the issue is somewhere else. In any case, I'm not very good with linux commands so google you problem and if no solution is working. Simply re-install apache.

Hope I Helped,
TheFreeElectron

Hi thank you for your reply i have now managed to get all the pins correct and working, BUT when clicking the buttons they are the opposite way round, when the button shows as on (green) it is actually off :/ I have looked at the code and tried editing it as well as changing the numbers from 1 - 8 rather than 0 - 7 and then restarted the pi. But nothing seems to of changed or updated.

Do i have to put something on the command line to update a file or rebuild it at all? Any help would be great.

Thank You

No problem!
I actually never had a such issue but the more you know about what's happening and the more likely you'll find the solution. The first way is to use the browser's developer's mode where you can see what the server gets and send back. It will tell you if the issue is somewhere on the server's side or rather on the client's one.

Normally, the only commands you need to type are the one written in this 'Ible. Also do not forget you can begin with a fresh start (re-installing the OS) so you should no longer have issues (this is a kind of last stand :)

Hope I Helped,
TheFreeElectron

Hi thank you for the reply, i now have everything working fine :) Is there any way i can change the button numbers to go from 1 - 8 ? And also what would i need to do to add two buttons, one for all on and one for all off?

Thanks

Glad to know it works!
Buttons are actually images so simply use paint or gimp to modify them.
For the two other buttons, add two of them to the index.php page then in the javascript and finally add two new functions to the gpio.php page; one switching everything on, the other off. Also, since the release of the 'Ible, I've successfully put the 8 (or ten buttons) in an array which makes the javascript MUCH cleaner so give it a try. ;)

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