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[Reply #15 on:]

Can someone try this?

Code:

const int x = 9600;
int *ptr;
//#define x 9600

void setup() {
   ptr = &x;
   Serial.begin(*ptr); 
}

void loop() {
 
}

What I'm trying to prove is that this will create the actual "const int" variable. Of course that the code will be bigger, but the memory footprint will include the const int variable because now there is pointer to it. (Yes, I'm assuming the compiler is not that smart)

[Reply #16 on:]

Just looks like a very long program to me, around 2,000 lines.
I had a program (several files compared with your one file), that grew to 2,700 lines and took 27K FLASH. It had lots of strings for LCD but I bet the difference between mine and your program is includes. I didn't have that many includes.

Two suggestions I can think off:
1) USE a 24LC512 EEPROM to store your English letters. Hope this won't slow you down too much. You'll have to try.
2) See if you're overloading any functions. Try not to overload. Say you have a constructor chips(int) and another one chips(long). If you used both, just because you didn't bother to convert long into int, the compiler stores both constructors in FLASH.

This can get significant with Serial.print(). Say you're already using the awesome sprintf, you should NOT use serial.print(int or float or long), only use serial.print(string). Use sprintf to construct a string and print with serial.print(string). Try serial.print(string) and serial.print(float) in one program and get rid of serial.print(float)

Code:

void setup()
{
  Serial.begin(9600);
}

void loop()
{
  Serial.print("3.14");
//  Serial.print(3.14);
}

This above program is only 1,894 on my 2009 and 3,726 if I uncomment the second line in loop!!!

[Reply #17 on:]

1) USE a 24LC512 EEPROM to store your English letters. Hope this won't slow you down too much. You'll have to try.

I don't see what you mean by English letters... do you mean strings?
Another possibility is to have commands (a couple of bytes) sent to the PC instead of a describing string. And multiply your floating points to 10 or 100 (depending on the size) and use those on the communication to the PC instead of floating point.

2) See if you're overloading any functions. Try not to overload. Say you have a constructor chips(int) and another one chips(long). If you used both, just because you didn't bother to convert long into int, the compiler stores both constructors in FLASH.

Also, great advice.

[Reply #18 on:]

What's english.h? It's not in your code. I suppose if it's a bunch of letter matrix for your persistent (?) display, you will need these matrix letters.

[Reply #19 on:]

Thank you everyone for looking over the code.  I can verify that replacing all of the

const uint8_t bla = xx;

with

#define bla xx

retained the exact code size.

@westwf  The font is pretty large, 8 bytes / char.  Most symbols use only 7x7 pixels so I could save 128 bytes there.  I had a quick look at the optiboot.  Looks like the way to go.

Thanks again!
Justin

[Reply #20 on:]

Can someone try this?

Code:
const int x = 9600;
int *ptr;
//#define x 9600

void setup() {
   ptr = &x;
   Serial.begin(*ptr); 
}

void loop() {
 
}

That doesn't compile which implies to me that the compiler knows you can't have a pointer to something that won't exist at run time.

______
Rob

 

[Reply #21 on:]

const int x = 9600;
const int *ptr;

//#define x 9600

void setup() {
   ptr = &x;
   Serial.begin(*ptr);
}

void loop() {
 
}

What I remember from the GCC documentation...

"const" only uses storage (SRAM) if it appears in more than only module (source file).

"static const" nevery uses storage.

Except when the address is taken (like the example above) which forces the compiler to place the constant in memory.


In other words, so long as there is not a pointer involved, "#define" and "static const" are identical in terms of storage.  "static const" has the distinct advantage of also carrying the data-type.