Arduino notes

debug memory problems (out of RAM)

See Arduino Forum on memory usage. This function will return the amount of RAM free. This accounts for the stack and heap used.

int freeRam () {
  // __brkval is the address of the top of the heap if memory has been allocated.
  // If __brkval is zero then it means malloc has not used any memory yet, so
  // we look at the address of __heap_start.
  extern int __heap_start
  extern int *__brkval; // address of the top of heap
  int stack_top; 
  return (int)&stack_top - ((int)__brkval == 0 ? (int)&__heap_start : (int)__brkval); 
}

Serial.println(freeRam());