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Topic: [HELP] Memory Use (Read 804 times) previous topic - next topic

phm78

Jul 12, 2012, 07:08 pm Last Edit: Jul 12, 2012, 07:19 pm by phm78 Reason: 1
Hi all,
I use an Arduino Uno with a ATMEGA328P R3.
If I'm not mistaken, I thus has 2048 bytes of SRAM.

I have a program that uses the following memory:
Serial Buffer = 256 bytes. (I changed the library)
SERIN [200] = 200 bytes.
String for display on LCD = 24 bytes.
various variables such bytes = 10 bytes.
a total of I think 490 bytes.
And then my program works properly.
If I add an array SERINMODIF [92] or 92 extra bytes, my program does not work, as if I had a crush memory.
If anyone has any idea? calculation may be my memory is right?
Thank you for your help.
Philippe.

majenko

What are the data types of your variables?
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dxw00d


phm78

All variables are byte.

phm78

My code:


#include <LiquidCrystal.h>

LiquidCrystal lcd(18,19,14,15,16,17);

const byte patchreq[11] = {0xF0, 0x0, 0x21, 0x02, 0x00, 0x02, 0x11, 0x00, 0x00, 0x00, 0xF7};
byte SERIN[200];
byte PATCH[92];
byte i = 0;
byte a = 0;
byte index = 0;
byte checksumlu = 0;
byte checksum = 0;
byte b=0;

void setup()
{
  Serial.begin(31250);

  lcd.begin(16,2);
  lcd.clear();
  lcd.print("o0o FACTORY");
  lcd.setCursor(0,1);
  lcd.print("Serial SysEx ");
  delay(100);
  lcd.clear();
}

void loop()
{
  patchread();
  lcd.print(a);
  lcd.print(" ");
  lcd.print(SERIN[0], HEX);
  lcd.print(" ");
  lcd.print(SERIN[194], HEX);
  lcd.print(" ");
  lcd.print(checksumlu, HEX);
  lcd.print(" ");
  lcd.print(checksum, HEX);
 
  loop:
  goto loop;
}


void patchread()
{
  Serial.flush();
  Serial.write(patchreq,11);

  while(Serial.available() < 205)
  {
  }

  do {                   
    i = Serial.read();
  }
  while(i != 0xf7);

  index = 0;
  do
  {
    SERIN[index] = Serial.read();
    index++;
  }
  while(SERIN[index] != 0xf7);

  checksumlu = SERIN[192];
  checksumlu *= 16;
  checksumlu += SERIN[193];
 
  checksum = 0;
  for (index = 0; index < 92; index++)
  {
    i = (index * 2) + 8; 
    b = (SERIN * 16) + SERIN[(i+1)];
    PATCH[index] = b; // This line causes the problem <<<--------------------------------------------------
    checksum += b;
  } 
   
  a=SERIN[10];
  a *= 16;
  a += SERIN[11];
}

majenko

You're not taking into account the memory used by the core system (millis counter, plus many others), and the LiquidCrystal memory requirements.

Plus you have the stack on top of all that.

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majenko

I have around 1700 bytes available with an almost empty sketch.  If I try and allocate more than that in one solid chunk it causes instability.
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AWOL

put your strings in PROGMEM, and your code in code tags.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

PaulS

Also, tell us what version of the IDE you are using. For 1.0+, there are two serial buffers - one for incoming and one for outgoing - that are the same size.

Why are you using Serial.flush()? Do you understand what it does?

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