mbed PWM 操作

PWM 操作,先设置频率(周期的s数) 再写入占空比即可

#include "mbed.h"
PwmOut led(PB_0);


int main()
{
    // specify period first
    led.period(4.0f);      // 4.0f = 4 second period
    led.write(0.50f);      // 50% duty cycle, relative to period  0=high  1=low
    //led = 0.5f;          // shorthand for led.write()
    //led.pulsewidth(2);   // alternative to led.write, set duty cycle time in seconds
    while (1);
}