Arduino behaving weird

[LuisTheOne]

Hey Guys!

I hooked up my WS2812 Led Strip to my Arduino and programmed a Light-Mode, but i can't explain myself why the variable "a" isnt getting count up.

Code:

#include <FastLED.h>
#define LED_PIN 2
#define NUM_LEDS 25

CRGB leds[NUM_LEDS];
int segNr = 0;

void setup() 
{
  FastLED.addLeds<WS2812, LED_PIN, RBG>(leds, NUM_LEDS);
  FastLED.setMaxPowerInVoltsAndMilliamps(5, 500);
  FastLED.clear();
  FastLED.show();
  Serial.begin(9600);

  Serial.print("Setup 1: ");
  Serial.println(segNr);
  segNr = 15;
  Serial.print("Setup 2: ");
  Serial.println(segNr);
}

void loop()
{
  // put your main code here, to run repeatedly:
  //leds[0] = CRGB(255, 0, 0);
  //leds[1] = CRGB(0, 255, 0);
  //leds[2] = CRGB(0, 0, 255);
  
  nightrider();
}

void nightrider() 
{
  Serial.print("Anfang: ");
  Serial.println(segNr);
  
  if (segNr >= 25) 
  {
    Serial.print("Reset: ");
    Serial.println(segNr);
    
    segNr = 0;
  } 
  else 
  {
    Serial.print("Set 1: ");
    Serial.println(segNr);
    
    for (int i = 0; i <= NUM_LEDS; i++)
    {
      leds[i] = CRGB(255, 255, 255);
    }
    
    Serial.print("Set 2: ");
    Serial.println(segNr);
    
    leds[segNr] = CRGB(255, 0, 0);
  }

  FastLED.show();
  
  delay(500);
  
  segNr++;
  
  Serial.print("Ende: ");
  Serial.println(segNr);
}


void randomcoloreffect() 
{

  for (int i = 0; i <= 25; i++)
  {
    leds[i] = CRGB(random(0, 255), random(0, 255), random(0, 255));
  }

  FastLED.show();
  delay(1000);
}

My Serial output is really weird because im getting "0" at "Set1:" and "-1" at "Set2".But i dont know why the for loop effects the a variable.

 

Thanks for your help.

[akio123008]

58 minutes ago, LuisTheOne said:

the variable "a"

Is that "segNr"?

 

I can't tell immediately what exactly is going wrong here (I'm not that great of a programmer) but generally speaking global variables should be avoided.

Perhaps you can make segNr a local variable instead of a global one. It seems you only use this variable inside the nightrider() function so just declare the variable in there.

like this:

void nightrider() 
{
  int segNr = <whatever value is required>;
  
  Serial.print("Anfang: ");
  Serial.println(segNr);
  
  <rest of the function>

 

 

[cachethrash]

It's probably because of the bounds on the for loop. You have it got to "i<=25" but the array is only 25 elements, so accessing leds[25] is actually accessing the 26th element of the array, which doesn't exist. I would guess segNr is stored in the memory after leds[], so it's getting affected. You can try printing segNr in the loop body to verify.