【51串口通信计算器 + 51定时器计算器】 最近有朋友提到百度空间的下载链接都是坏的，因此上传到pudn,方便网友下载。 -【51+ 51 timer serial communication Calculator Calculator】 Recently, a friend mentioned that Baidu Space download link is bad, so upload pudn, to facilitate users to download.

51单片机，三极管驱动蜂鸣器，带ISIS仿真（源代码从下载PUDN仿真自己做的）-51, transistor drive buzzer with ISIS simulation (source code from the download PUDN simulation do their own)