If you want to create QR codes dynamically on your website, you can use the class from http://phpqrcode.sourceforge.net/
The usage is pretty simple. In this example I created an image php file:
This outputs date and time into a QR code and outputs a PNG file. In the HTML file we only have to show the image:
The QR code looks like that (if you do a refresh in the browser the code will change):
And that’s it. More documentation can be found on the projects homepage.
Here is the complete example as download.