bp_drag

仿真程序数控机床，数控机床，以模仿实际操作，有有一定的价值，很多共享！,可以直接使用。 (Simulation program CNC machine tools, CNC machine tools, to mimic the actual operation, the value of many shared Can be used directly.)

数字开关测试的源程序，非常适合新51单片机的新手入门的学习。(Digital switch test source program, very suitable for novice start learning new 51 single-chip microcomputer.)

18B20电路图,温度传感器，汇编版与C语言版共有及51开发板上的连线(The 18B20 schematic, temperature sensor, assembly version of the C language version of Total and 51 development board of the connection)

This is LM3S9B92 Sample Code data

松下车载碟机的协议代码，用于多种汽车的原车配备机头的扩展协议(Panasonic Car turntables protocol code, the original car used in a variety of vehicles equipped with head of the extended protocol)

iic接口的程序，可以用于f149单片机(iic interface procedures can be used F149 microcontroller)

使用STM32F4+usb3300实现虚拟示波器,支持使用外部ADC模式，也就是使用AD9280芯片，最大采样率可达30MSPS.(STM32F4+usb3300 implementation of the virtual oscilloscope, support the use of external ADC mode, that is, the use of AD9280 chip, the maximum sampling rate of up to 30MSPS )

LED点阵，多种不同的显示图样，静态动态显示，有应用(LED dot matrix, a variety of different display patterns, static dynamic display applications)

YL_3串行数码管显示时钟，74HC595，8位，显示时分秒，自动计数。(YL_3 serial digital display clock, 74HC595, 8 bit display minutes and seconds, automatic counting.)

说明：  下面的程序利用友元函数求两点间的距离。请你将有关的程序补充完整，并总结为什么这里要用友元函数来求两点间的距离。(using friend to get the result.)