目 录
摘 要................................................................................................................................I
ABSTRACT .....................................................................................................................II
绪 论 ...............................................................................................................................1
1 方案论证 .....................................................................................................................2
2 微处理器 89C51 .........................................................................................................4
2.1 89C51 的外部引脚.......................................................................................................4
2.2 89C51 的内部结构.......................................................................................................5
3 A/D 转换器 0809.........................................................................................................8
3.1 主要性能 ....................................................................................................................8
3.2 ADC0809 芯片组成原理 ..............................................................................................9
3.3 ADC0809 引脚功能 .....................................................................................................9
3.4 ADC0809 与 89C51 的硬件接口 .................................................................................10
4 声光报警和 K 型热电偶放大电路 ..........................................................................12
5 键盘设计....................................................................................................................13
5.1 键盘接口的输入和去抖动..........................................................................................13
5.2 独立式键盘及其接口.................................................................................................13
5.3 行列式非编码键盘及其接口 ......................................................................................14
5.3.1 程序扫描方式.....................................................................................................14
5.3.2 定时扫描方式.....................................................................................................15
5.3.3 中断扫描方式.....................................................................................................16
6 89C51 与继电器连接电路........................................................................................17
7 LED 显示...................................................................................................................18
7.1 LED 显示驱动器 MC14489........................................................................................18
7.1.1 硬件结构............................................................................................................18
7.1.2 工作原理............................................................................................................19
7.1.3 MC14489 与单片机的接口 ...................................................................................21
8 串行通信接口选择....................................................................................................22
8.1 RS—232C 接口 .........................................................................................................22
8.1.1 电气特性............................................................................................................22
8.1.2 电平转换............................................................................................................23
