How much ram is being used?

Forum 2005-2010 (read only) Hardware Troubleshooting
20

I agree that reporting memory usage at compile time (from the elf file) would be very welcome, but for runtime use, having the get_memory_free function in a library would make the basic info accessable through just including the header instead of having to copy and past the code - Here is the function as a library:

Save as MemoryFree.h in a library directory called MemoryFree

// memoryFree header

#ifndef      MEMORY_FREE_H
#define MEMORY_FREE_H

#ifdef __cplusplus
extern "C" {
#endif

int freeMemory();

#ifdef  __cplusplus
}
#endif

#endif

Save as MemoryFree.c in the same library directory

 /*
 * MemoryFree.c
 * returns the number of free RAM bytes
*/

#include "WProgram.h"  
#include "MemoryFree.h"

extern unsigned int __data_start;
extern unsigned int __data_end;
extern unsigned int __bss_start;
extern unsigned int __bss_end;
extern unsigned int __heap_start;
extern void *__brkval;


int freeMemory()
{
  int free_memory;

  if((int)__brkval == 0)
     free_memory = ((int)&free_memory) - ((int)&__bss_end);
  else
    free_memory = ((int)&free_memory) - ((int)__brkval);

  return free_memory;
}

Usage in a sketch:

#include <MemoryFree.h>

void setup()                    // run once, when the sketch starts
{
  Serial.begin(9600);
}

void loop()                     // run over and over again
{
  Serial.print("freeMemory() reports ");
  Serial.println( freeMemory() );
}