On the NetTuts.com site today they've posted the first part of a series showing the integration of the BitPay bitcoin payment service into an OpenCart instance. In this first part they focus on getting some of the initial setup and administration handling set up.
In this series, we are going to look at building a Bitcoin payment system into our installation of OpenCart. Before we get started, I recommend that you practice the basic OpenCart module development if you are not familiar with how to build your own modules. Once done, you should have enough knowledge to continue with developing more advanced modules. In this series, that's exactly what we aim to do.
They start by having you download the BitPay API library and dropping it into the root directory of your OpenCart installation. Next they show you how to create an "Admin" controller with the data you'll need to pass into the view including data pulled from a model. They also create the admin view showing the current orders using bitcoin as payment, their status and options to change the speed of the API requests, status and toggling test mode on and off. Finally they include the code to save the results of the admin form submission and a bit of validation around user permissions and API key validity.