* 1) 按键状态说明：

* 按键采用查询方式判断，每检测一次将以前状态向左移动一位并记录最新检测状态。

* 按键状态只取低三位：

* 000 - 没有检测到按键动作

* 001 - 第一次检测到按键动作

* 011 - 按键稳定闭合

* 111 - 按键持续闭合

* 110 - 第一次检测到按键释放

* 100 - 按键稳定释放

* 010 - 正脉冲抖动干扰,状态置为 000

* 101 - 负脉冲抖动干扰,状态置为 -* 1) Key Status Descr iption:* keys using queries judgments, each will be tested once left a previous state and record the latest detection status.* Low-key status only take three:* 000- did not detect keystrokes to 001- first detected keystroke* 011-* 111 keys stable closure- Button continued closed* 110- first detected key released* 100- Button stable release* 010- positive pulse jitter interference, the state is set to 000* 101- Negative pulse jitter interference, the state is set to 111