自製PWM 的小工具

先安裝wiringPi


使用   GPIO 4 , GPIO 17, GPIO 18, GPIO24 (not pin number..)

使用四條杜邦線....從上面四個 GPIO .... 聯到你要量的四個點....

然後執行

g++ -Wall -o PWM pwm.cpp -lwiringPi

sudo ./PWM 即可


pwm.cpp 程式碼如下:

#include <math.h>
#include <wiringPi.h>
#include <stdio.h>
#include <stdlib.h>
#include <wiringPiI2C.h>
#include <string.h>

int PWM_PIN0 =  7; // GPIO 4
int PWM_PIN1 =  0; // GPIO 17
int PWM_PIN2 =  1; // GPIO 18
int PWM_PIN3 =  5; // GPIO 24

void  measure(int PWM_PIN);

PI_THREAD (myThread0)
{
  for (;;)
  {
     measure(PWM_PIN0);
    delay (500) ;
  }
}

PI_THREAD (myThread1)
{
  for (;;)
  {
     measure(PWM_PIN1);
    delay (500) ;
  }
}

PI_THREAD (myThread2)

{

  for (;;)

  {

     measure(PWM_PIN2);

    delay (500) ;

  }

}

PI_THREAD (myThread3)

{

  for (;;)

  {

     measure(PWM_PIN3);

    delay (500) ;

  }

}

int main (void)
{
  int x;
  wiringPiSetup () ;
  x = piThreadCreate (myThread0) ;
  if (x != 0)
     printf ("it didn't start\n");

x = piThreadCreate (myThread1) ;
  if (x != 0)
     printf ("it didn't start\n");

x = piThreadCreate (myThread2) ;
  if (x != 0)
     printf ("it didn't start\n");

x = piThreadCreate (myThread3) ;
  if (x != 0)
     printf ("it didn't start\n");

  for (;;)
  {
    delay (500) ;
  }
  return 0 ;
}

void  measure(int PWM_PIN)
{
    unsigned int start,mid,end,temp,diff;
    while(digitalRead(PWM_PIN)==HIGH)
    {

    }
    while(digitalRead(PWM_PIN)==LOW)
    {
    }

    start = micros();

    while(digitalRead(PWM_PIN)==HIGH)
    {
    }

    mid = micros();

    while(digitalRead(PWM_PIN)==LOW)
    {
    }

    end = micros();

    diff = mid - start;
    temp = (diff * 100) / (end-start);
    printf("pin : %d, pulse : %d us,  PWM : %d,  Freq : %d \n",PWM_PIN,diff,temp,1000000/(end-start));
}