7、汽车脉速和里程表

用单片机设计一个汽车脉速和里程表，能够同时显示当前的脉速和里程，在上述基础上可以用键盘设置最高车速报警，当车速超过设定时用蜂鸣器或者指示灯进行报警。可以用数码管或者液晶屏显示脉速和里程，设置车速报警时可以和脉速公用同一组显示器件，其它电路自由发挥。

设计提示：汽车车轮转动速度，可以用示例程序（50-产生多路不同频率方波）来模拟，也可以用第8题可变频率方波发生器来模拟。-7, auto pulse speed and odometer Using SCM to design a car speed and odometer, can at the same time show the current pulse speed and range, on the basis of the above can be set with the keyboard top speed alarm, when the speed more than set by the buzzer or light alarm. Can use the digital tube or LCD display pulse speed and mileage, speed alarm when can and pulse rate of the public the same set of display devices, free play other circuits. Design tip: car wheel rotation speed, can use the sample program (50- to produce multiple different frequency square wave) to simulate, 8 topic variable frequency square wave generator can also be used to simulate.