Raspberry Pi是什么？
引用维基百科的一句话：
The Raspberry Pi is a credit card sized single-board computer developed in the UK by the Raspberry Pi Foundation with the intention of stimulating the teaching of basic computer science in schools.
简单地说，它就是一个基于ARM CPU的、信用卡那么大的迷你计算机。
In short, Pi is an ARM-based mini computer which has a credit card size.
在阅读本文之前，请确保你已经阅读过我的另外几篇关于Pi的文章，因为本文与它们有或多或少的关系。
Before reading this article, please make sure that you've read some other articles of mine on Pi, because this article is more or less based on them.
通过Raspberry Pi的GPIO口来控制发光二极管已经不是什么新鲜事了，网上有大量的教程和资源可查。为了测试一下控制GPIO输出的功能，我也实践了一次。
首先声明，我对硬件并不了解，所以下文可能有错误，如果你发现了，请留言告诉我，非常感谢。
It's nothing new to control LEDs through Pi's GPIO, a lot of tutorials & resources are available on the Internet now. But I tried to do it myself too for the sake of testing the GPI output functionality.
First I want to remind the readers that I'm not a hardware guy so this article may contains some mistakes, and if you find that, please leave comments to tell me, thanks in advance.
文章来源：http://www.codelast.com/
【1】实验目的 / Experiment purpose
写一个简单的程序，控制Raspberry Pi的GPIO口输出高、低电平，从而让接在GPIO口上的发光二极管闪烁。
Write a simple program to control the GPIO on Pi to output high or low level to make the LED which connected to GPIO blink.