30720 bytes maximum sketch size, if not enogh?

what if we need more space in large project?

i know loop helps but if we need more space?


i know loop helps but if we need more space?

You youngsters thinking 30k is too small an area to work in; why, back in my day with 8-bit home computers it would be a luxury to have such an amount of memory!

/oldster rant mode off


If you are at a point where you need more memory for code, and you have exhausted all possibilities for reducing the size of your code to fit (ever heard of a 4k intro?), then you either move to another micro-controller with a larger program memory (such as the Mega), or you use other approaches.

Perhaps before you finalize your design, look and see if it can be made distributed and parallelized - if it can, then you could possibly use multiple Arduinos (or ATMegas), communicating over SPI/I2C in a master/slave relationship, and break the code up among each.

For instance, say you were building an Arduino-based handheld game system - you could try to put everything into a single Arduino (sound, LCD control, button sensing - oh, and the game itself), but this wouldn't be the best method.

It would be better to have one Arduino be the dedicated "master" - which would probably also hold the game and the SPI/I2C interface to the other Arduino/ATMegas. These other devices, hanging off the SPI/I2C bus, would each control one aspect of the system. One could control the LCD (maybe a KS0108 display), one could read the buttons, and one could play music and sound effects. The master device would be responsible to coordinate and interface with all of this, but you would likely write a special library for that anyhow to abstract the details away from the actual game code.

A similar thing could be done with a robot; one master could coordinate other slave devices to act as motor controllers, sensor interfaces, or other tasks. Note that this strategy should always be given thought, and should be a possible tool in your toolbag - whether you are working with micro-controllers or networked mainframes.


Hey Pluggy; what's that weird standalone brace for after the analogRead()?


A little something I was playing around with earlier, its the tail end of an if then structure........


 Stephen's Blink and long term clock clock accuracy


int ledPin =  13; // LED connected to digital pin 13
unsigned long time;
unsigned long secloop = 1000;
unsigned long fred;
unsigned long count = 0;
int ana;
boolean liteon = false;

// The setup() method runs once, when the sketch starts

void setup()   {                
  // initialize the digital pin as an output:
  pinMode(ledPin, OUTPUT);     

// the loop() method runs over and over again,
// as long as the Arduino has power

void loop()                     
  count = count + 1;
  time = millis();
  if (count >= 100){fred = count / 10 * 22;
  ana = analogRead(1);};
  if (time >= secloop){
    secloop = secloop + 500;
    if (liteon){
      digitalWrite(ledPin, HIGH); 
      Serial.print(" : ");
      Serial.print(" : ");
      count = 0;
      liteon = false;
      digitalWrite(ledPin, LOW); 
      liteon = true;

Looking again, it starts on the line above in the screenshot. ;)

Probably a superfluous semi-colon in there somewhere........

arduinoMega is great but i am using stand alone chip.

Split it up into several modules and use more than one chip as suggested by cr0sh.

I have a large project that uses 2 328s and 2 168s communicating by serial.

Do you need this size for program or for data? In case of data an eprom / SD card may do the trick.


cr0sh, the open curly brace is in the line above. I don’t like this bracing style, myself, for exactly this reason.

I'd wondered about using an SDcard to hold code which can be swapped in and out. I have no idea about how to accomplish that.

An SD card would be good only for data. However, if you are running an interpreter, then code basically becomes data. Then of course the SD card can hold your code. If you do not mind to go for something like forth this can give you pretty good performance as well. However I see no way to put "Arduino code" into an SD card such that it can be executed with reasonable performance. Unless you course you go so far as to self flash the Arduino from the SD card. Something that is most probably very far stretched.


you have exhausted all possibilities for reducing the size of your code to fit

Sorry for bringing back a live such old topic, but while still developing code, I see the maximum size of my sketch closing in quickly. Even already came to issues where the sketch did not fit on a UNO anymore, fortunately the Duemilanove does still handle it.

But I do want to add more functionality and now seek ways to optimize my code. Anyone can guide me into some directions? There must be some general optimization guides or … ?

But I do want to add more functionality and now seek ways to optimize my code. Anyone can guide me into some directions? There must be some general optimization guides or ... ?

Hallo Erwin,

yes, there are general optimisation guides. They include pearls of wisdoms like reusing code, not including stuff you don't need, reducing string table sizes by tail end compression and many other things. But all those things work only, if your code suffers from the problem a measure is trying to alleviate. So before you go out and optimise away, you should try to understand what takes all the space in your code.


Instead of arduino mega as some suggested, why not sanguino? It has twice the memory of an 328 arduino, not to mention the number of analog and digital i/o and its in DIP :D

Can’t we just replace the chip with other but only with more available memory?

There is no "bigger" Atmel chip with the 328 form factor.

thanks for your reply.
Well, thats bad news, i have to get other way, maybe with a SD card, but the problem is that I don’t have free pins for SD card.

lets see…

I reckon there's a fair chance that the Arduino saved the DIP package for the 328. There's no good reason to use that package in a commercial product these days.

First I have to optimize the code, i belive i can get some free space, if not, maybe i will use one of this:

I2C EEPROM - 256kbit http://www.sparkfun.com/products/525