LED点阵字符显示原理.ppt

数字化医疗仪器第三章第三章数字化医学仪器数字化医学仪器人机接口人机接口 Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 第三章数字化医学仪器人机接口 键盘与接口键盘与微机的接口包括硬件和软件二部分。硬件: 键盘结构及与主机的连接方式。软件: 键盘管理程序。 键盘输入基础知识一. 键盘的组织 1. 编码式键盘键和专用键盘编码器构成. 有键按下,自动生成键值。例如: MM5740AA 芯片; INTEL 8279 等。 2. 非编码式键盘(本章介绍)不含编码器,键盘只送出一个简单的闭合信号,对应的键值需有软件来译出。 Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 1)独立式键盘图 3-1(a) 特点:一键一线. 优点:结构简单,:占用较多检测线,不便组成大型键盘. 2)矩阵式键盘图 3-1(b) 特点:把检测线分成二组,一组为行线,另一组为列线,按键放在行线和列线的交叉点上. 优点::键盘分析程序较复杂. 键盘的工作方式 a) 编程扫描方式(查询方式) b) 中断工作方式 c) 定时扫描方式 Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 三. 键抖动及消除键抖动可能导致计算机将按键操作识别为多次操作. 可采取以下措施: Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. (1) 硬件电路消除法(2) 软件延时法当判定按键按下时,用软件延时 10ms~20ms ,等待键稳定后重新再判一次,以躲过触点抖动期。 Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 四. 键连击的处理图 3-4