说明：  * 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 111
(* 1) Key Status Description:* 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)