目 录
1 绪论 ....................................................................................................................................................... 1
1. 1 选题背景及其意义 .................................................................................................................... 1
1. 2 本课题研究内容 ........................................................................................................................ 2
1. 3 本课题设计思路 ........................................................................................................................ 2
1. 4 功能描述 .......................................................................................................................................3
2 基于单片机的电子天平的硬件设计.....................................................................................4
2. 1 基于单片机的电子天平的硬件方案设计............................................................................ 4
2. 2 称重传感器....................................................................................................................................4
2. 3 电子天平专用 24 位 AD 转换芯片 HX711 及其电路.......................................................... 6
2. 4 单片机 STC89C52 及其电路...................................................................................................... 8
2. 5 液晶屏电路..................................................................................................................................12
2. 6 矩阵键盘电路..............................................................................................................................14
2. 7 声光报警电路..............................................................................................................................15
2. 8 电源电路.......................................................................................................................................15
3 Protel 硬件开发软件...................................................................................................................16
3. 1 Protel 软件组成.......................................................................................................................16
3. 2 PCB 板设计..................................................................................................................................18
4 软件设计..............................................................................................................................................21
4. 1 主程序设计..................................................................................................................................21
4. 2 子程序设计..................................................................................................................................22
5 下载、调试与使用..........................................................................................................................23
5. 1 USB 转串口驱动安装................................................................................................................23
5. 2 下载程序.......................................................................................................................................23
5.3 上电运行.......................................................................................................................................25
5.4 键盘操作说明 ...........................................................................................................................25
5.5 常用使用步骤.............................................................................................................................26
6 结论........................................................................................................................................................27
参考文献................................................................................................................................................. 28
致谢 ...........................................................................................................................................................29
附录 ...........................................................................................................................................................30
