How to call function with infinite-loop? - c

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

Yes you will need a separate thread, or some other form of asynchronous execution. Once you enter that while loop, no other code runs in that thread. Ever.

Answer 2

If I understand correcctly nothing works in your integrated version. In that case, yes you probably need to run the infinite loop on a separate thread, because your function with the infinit loop will never exit, so no other code will ever run on that thread.

Answer 3

You don't say what OS, but yes, set it as a low-priority thread, minimal stack size. I flash a LED in my projects, just so I can easily see if the code has reached the abort-handler yet :)
void LEDflash_task_code(void *p)
{
while (1)
{
FIO1CLR=STATUS_LED;
OSsleep(750);
FIO1SET=STATUS_LED;
OSsleep(250);
};
};

Answer 4

If you have access to hardware peripheral timers (any micrcontroller/microprocessor application), you should use those hardware timers, not threads nor software sleep().
void init_toggle_led (uint32_t interval)
{
setup_hardware_timer(interval);
}
void toggle_led (void)
{
if( (hardware_timer_register & flag) > 0 )
{
port = port ^ pin_mask;
}
}
main()
{
init_toggle_led(1000);
for(;;)
{
do_stuff();
toggle_led();
}
}
This was an example with polling. Alternatively, you can use hardware interrupts from the timers and toggle the port from there.

Answer 5

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);
}
}

Answer 6

I think you need to implement as a watchdog functionality. Because if you use threads then even if other threads has some issues(like deadlock), your LEDs will toggle as long as toggle_led thread works. You need to implement an toggle_led() function and call from each of other threads /functions before returning to make sure all other threads/functions are getting executed successfully without waiting continuously for some resources