采用LPC2138做控制器，利用PWM控制发射头发射超声波，然后利用定时器的捕获功能得到接收超声波的时间。-Done using LPC2138 controller, using PWM control launching the first launch wave, and then using the timer capture function was to receive ultrasonic time.

用LPC2138实现风扇控制及转速获取，采用定时器的PWM和CAP方式分别进行设置和获取转速-use LPC2138 to contrl fan speed level and capture fan current speed ,use PWM to contrl fan speed and use cap to capture fan speed

LPC2138 PWM proteus 仿真程序-LPC2138 PWM proteus simulation program