介绍UPD6121的引脚功能及编码过程和使用方法-UPD6121 introduce the pin function and encoding processes and the use of methods

一篇讨论红外解码的文档，特别是说明了空调控制码的实现方式与解码机制，比如upd6121.-An article in describing the decoding method of infrared control codes. The most interesting part is about to fully describe the implementation method of HVAC control codes such as upd6121