Interfase trouble with the raspberry pi 3 (Analog output)

Jelle

Hello,

I am having trouble with the analog output. I did supply the PWM signal at 400Hz from GPIO18. This PWM signal was measured to make sure that it was there and I tried differed duty cycles. Is there something else that I am missing. Should the jumper wires be in a specific setting or maybe something else?

Martin Kudláček

Hello @Jelle,
can you please share how exactly did you proceed with setting up the PWM signal?

Thanks,
Martin

Jelle

I use the wiringPi library so to run this code you should install wiringPi

#include <stdio.h>
#include <unistd.h>
#include <stdint.h>

#include "wiringPi.h"

void gpioSetupCostum()
{

  printf("gpioSetup has started\n");
  wiringPiSetupGpio ();
  usleep(1000);
  printf("wiringPiSetupGpio was a succes\n");

  pinMode(18, PWM_OUTPUT);
  usleep(1000);
  printf("pinMode was a succes\n");

  pwmSetMode(PWM_MODE_MS);
  usleep(1000);
  printf("pwmSetMode was a succes\n");

  pwmSetRange(1024);
  usleep(1000);
  printf("pwmSetRange was a succes\n");

  pwmSetClock(47);
  usleep(1000);
  printf("pwmSetClock was a succes\n");
  
}

void gpioClose()
{
  pwmSetMode(PWM_MODE_BAL);
  usleep(1000);
  pinMode(18, INPUT);
  usleep(1000);
}


int main()
{
  int GPIOCounter, SampleCounter;
  double PWM[11]={0, 1 , 2 , 3, 4, 5, 6, 7, 8, 9, 10};
  const int len = 11;	
  int AmountOfSamples = 200;  
  printf("Start setup\n");
  gpioSetupCostum();
  printf("Finish setup\n");
  
  printf("Start reading input ports\n");
  for(SampleCounter =1; SampleCounter <= AmountOfSamples; SampleCounter++){
    printf("Sample = %d\n", SampleCounter);
	for(GPIOCounter = 0; GPIOCounter < len; GPIOCounter++){
	  printf("PWM input = %.1f\n", PWM[GPIOCounter]);
	  pwmWrite(18, (int)((PWM[GPIOCounter] * 1024)/10));
      usleep(1000000);
    }	
  }	
  
  gpioClose();
}