基于msp430，5线拓展25按键扫描，状态机编程。已通过测试，工作稳定，消抖效果好，附有原理介绍和原理图。-based on MSP430 25 key scan state with only 5 IOs. machine programming. Has been tested, stable, can eliminate buffeting effectivly, with a schematic presentation and schematic.