Question

I need help to clear my concepts.
I have a function which toggle the Led status on/off after every second. Now the code for the on/off runs inside infite loop.

Example:

  void ToggleLed( int pin_number)     
  {      
      // some code  
      while(1)    
      {    
          // code to execute the Led status    
      }   
  }     

Now when I integrate this code with base line and called that function inside other function it just doesnt work no other functionality of software works.

Question: Function has infinite-loop and that it doesn’t come out of control and other functions called after that function doesn’t work.
If that is the case do I need to provide separate thread to it?

Any suggestion will be helpful.

Answer 1

As David mentioned, you should run your LED code in a separate thread. http://www.yolinux.com/TUTORIALS/LinuxTutorialPosixThreads.html#BASICS

Once you have threads, if you want your code to be able to stop your LED from blinking, then add a flag that’s checked inside the while loop at each iteration, and if it’s set then break out.

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

void * toggle_led(void *ptr);
int stop=0;

int main (int argc, const char * argv[])
{
    printf("Hello, World!\n");

    // set up thread
    pthread_t LED_thread;
    char * message = "blink!";
    pthread_create( &LED_thread, NULL, toggle_led, (void*) message);

    // do some other work
    sleep(5);

    // ok you want to quit now
    stop=1;
    pthread_join(LED_thread, NULL);
    printf("Goodbye!\n");
    return 0;
}

void *toggle_led(void *ptr)
{
    while (!stop)
    {
        printf("%s \n", (char *)ptr);
        sleep(1);
    }
}