Error to create header file and use CRGB LED array from FastLED library

Question

I'm working on Arduino project with addressable LEDs and I'm using the FastLED.h library.

To simplify my program, I want to create a library called LedsHorloge.h from which one I'll call the function Jauge(int tour, int numberLeds, int brightness, CRGB* ledTable) to light up my LED strip.

I'm newbie in C++.

In the Arduino IDE, this is the error I get:

D:\Programmation\Arduino\libraries\libraries\JaugeLED/LedsHorloge.h:16:8: note: void LedsJauge::Jauge(int, int, int, CRGB*)

   void Jauge(int tour, int numberLeds, int brightness, CRGB* ledTable);

        ^

D:\Programmation\Arduino\libraries\libraries\JaugeLED/LedsHorloge.h:16:8: note:   no known conversion for argument 4 from 'CRGB (*)[32]' to 'CRGB*'

exit status 1
no matching function for call to 'LedsJauge::Jauge(int&, int, int, CRGB (*)[32])'

This error happens when I run this code in the Arduino IDE:

#include <LedsHorloge.h>
#include "FastLED.h"

#define LED_PIN     6
#define NUMBER_LEDS    32
#define BRIGHTNESS  100
#define LED_TYPE    WS2812B
#define COLOR_ORDER GRB
#define VITESSE_JAUGE 150 // Delay milliseconds

CRGB leds[NUMBER_LEDS];

#define UPDATES_PER_SECOND 100

int tour = 0 ; // Compte le nombre de tour dans le loop
int pinButton = 8; // Pin qui déclenche la fonction "Jauge"
boolean flag = false ;

LedsJauge jauge(LED_PIN); // This is the object I create 

void setup() {

    delay( 3000 ); // power-up safety delay
    FastLED.addLeds<LED_TYPE, LED_PIN, COLOR_ORDER>(leds, NUMBER_LEDS).setCorrection( TypicalLEDStrip ); // Initialisation de la bande de leds

    Serial.begin(9600);
    FastLED.clear(); // Fonction d'initialisation, encore mal connue

    pinMode(pinButton, INPUT_PULLUP) ;
    InitBandeLeds(); // Eteint toutes les leds si elles sont allumées

    FastLED.show();  // Applique la valeur HSV définie dans la variable "leds"
}

void loop() { 

  // tant que le bouton n'est pas activé, le drapeau reste false
  if ( digitalRead(pinButton) == LOW ){
    flag = true ;
  }


  // lorsque le drapeau devient true on rentre dans la condition
  if (flag){
      if ( tour < NUMBER_LEDS ){  tour += 1;  } // A chaque loop la variable est incrémenté de 1

      jauge.Jauge(tour, NUMBER_LEDS, BRIGHTNESS, &leds); // ERROR COMES FROM THIS LINE
      FastLED.show(); 
      FastLED.delay(1000 / UPDATES_PER_SECOND);
      delay(VITESSE_JAUGE); // régle la vitesse d'allumage des leds
  }

}


// Fonction qui éteint le bandeau de leds
void InitBandeLeds(){
    for( int i = 0; i < NUMBER_LEDS; i++) {
        if ( tour - i >0 ){
          leds[i] = CHSV( 0, 0, 0) ;
        }
    }  
}

This is my header called LedsHorloge.h

#ifndef LedsHorloge_h
#define LedsHorloge_h

#include <Arduino.h>
#include "FastLED.h"

class LedsJauge
{
 public:
 LedsJauge(int pin);
 // A chaque tour une led supplémentaire de la jauge est allumée
 void Jauge(int tour, int numberLeds, int brightness, CRGB* ledTable);
 private:
 int _pin;
};


#endif

This is my source code called LedsHorloge.cpp

#include <Arduino.h>
#include "FastLED.h"
#include "LedsHorloge.h"

LedsJauge::LedsJauge(int pin)
{
 _pin = pin;
}

void LedsJauge::Jauge(int tour, int numberLeds, int brightness, CRGB* ledTable)
{
    for( int i = 0; i < numberLeds; i++) {
        if ( tour - i >0 ){
          ledTable[i] = CHSV( 100, 187, brightness) ;
        }
    }

 return;
}

I don't know how to make a pointer on the object CRGB leds[NUMBER_LEDS];.

score 0 · Answer 1 · answered Jul 17 '18 at 06:50

I get the answer from another forum, the solution is to replace :

jauge.Jauge(tour, NUMBER_LEDS, BRIGHTNESS, &leds);

By

jauge.Jauge(tour, NUMBER_LEDS, BRIGHTNESS, leds);

However, I don't really understand why I must not use the memory value of the variable whereas I use a pointer in the declaration of the function Jauge, let's see :

void LedsJauge::Jauge(int tour, int numberLeds, int brightness, CRGB* ledTable)

score 0 · Answer 2 · answered Apr 18 '21 at 11:54

0

That's because

    CRGB leds[NUMBER_LEDS];

leds is already a pointer; only that it's a const pointer. i.e. one cannot change the address of the variable.

answered Apr 18 '21 at 11:54

Muppalla Sree Surya Prakash

1
1

Note that `leds` is *not* a pointer, it's an array. However, arrays decay to pointers (to their first element) when used as parameters in function calls. – Adrian Mole Apr 18 '21 at 13:51

Error to create header file and use CRGB LED array from FastLED library

2 Answers2