This function places the current value of the heap and stack pointers in the variables. You can call it from any place in your code and save the data for outputting or displaying later. This allows you to check at different parts of your program flow. The stack pointer starts at the top of RAM and grows downwards. The heap pointer starts just ab…

arduinoMemory.cpp

//This function returns the amount of RAM currently in available
uint8_t * heapptr, * stackptr;

void check_mem() {
  stackptr = (uint8_t *)malloc(4);          // use stackptr temporarily
  heapptr = stackptr;                     // save value of heap pointer
  free(stackptr);      // free up the memory again (sets stackptr to 0)
  stackptr =  (uint8_t *)(SP);           // save value of stack pointer
  Serial.print(F("Heap: "));
  Serial.println(*heapptr);
  Serial.print(F("Stack: "));
  Serial.println(*stackptr);
}

//This function returns the amount of RAM currently in use
int getMemory() {
  int size = 1024; // Use 2048 with ATmega328
  byte *buf;
 
  while ((buf = (byte *) malloc(--size)) == NULL);
 
  free(buf);
  return size;
}