ipod专用IC的PDF文档，可以通过简单控制IC的电平控制IPOD，适合IPOD二次开发.-ipod-specific IC PDF documents, you can simply control the IC level control IPOD, IPOD for secondary development.

一份介绍手机电子罗盘原理的文档，值得研究借鉴。-An introductory phone electronic compass principles document.