In this tutorial, we will create a web server on pcDuino using Python. We can then control/read GPIOs on pcDuino through the webpage. This is a prefect implementation of web lamp or any web powered devices.

1. Install Requests (Requests is a HTTP client library of Python):

1. $ sudo apt–get install python–requests

2. Install python-pip (pip is the tool used to install and manage python software packages):

1. $sudo apt–get install python–imaging python–imaging–tk python–pip python–dev git

Note: Some time the above commands will fail, we need:

1. $sudo apt–get update

3. Install Flask (Flask is a light weight web application framework written by Python)

1. $sudo pip install flask

4. Download python-pcduino from github, and put it under /home/ubuntu. Enter into directory Sample, and copy directory blink_led to a directory named hellp-gpio, and rename the file blink_led.py there to hello-gpio.py.

The code of hello-gpio.py is as following:

1. from flask import Flask, render_template
2. import datetime
3. import gpio
4.  
5. app = Flask(__name__)
6.  
7. channel = { 0:‘gpio0’, 1:‘gpio1’, 2:‘gpio2’, 3:‘gpio3’, 4:‘gpio4’,
8. 5:‘gpio5’, 6:‘gpio6’, 7:‘gpio7’, 8:‘gpio8’, 9:‘gpio9’,
9. 10:‘gpio10’, 11:‘gpio11’, 12:‘gpio12’, 13:‘gpio13’
10. }
11.  
12. @app.route(“/”)
13. def hello():
14.  
15. now = datetime.datetime.now()
16. timeString = now.strftime(“%Y/%m/%d %H:%M:%S”)
17. templateData = {
18. ‘title’:‘HELLO!’,
19. ‘time’:timeString
20. }
21. return render_template(‘main.html’,**templateData)
22.  
23. @app.route(“/readpin/”)
24. def readPin(pin):
25.  
26. gpio.pinMode(channel[int(pin)],gpio.INPUT)
27. value = ” “
28.  
29. if (gpio.digitalRead(channel[int(pin)]) == gpio.HIGH) :
30. value = “Read GPIO” + pin + ” is high !”
31. else :
32. value = “Read GPIO” + pin +” is low !”
33. templateData = {
34. ‘title’ : ‘Status of GPIO’ + pin ,
35. ‘value’ : value
36. }
37. return render_template(‘pin.html’,**templateData)
38.  
39. if __name__ == “__main__” :
40. app.run (host=‘0.0.0.0’,port=80,debug=True)

5. Create a directory named templates under directory hello-gpio, and create two files there “main.html” and “pin.html’:

The content of file ‘main.html”:

The content of ‘pin.html’ is as following:

6. Type “$sudo python ./hello-gpio.py” to run the code:

7. Check IP address of pcDuino using “$ifconfig”:

8. Open a web browser on a PC that shares the same network, and enter the IP address of pcDuino found in step 7:

Enter 192.168.35/readpin/0 (this is to read GPIO 0), we will see :

192.168.35/readpin/7 will read GPIO 7.