I am writing a library for my program that uses FastLED in some of

Archive FastLED Archive
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1

I am writing a library for my program that uses FastLED in some of the private methods and I am unsure how to make sure that the FastLED library should be included. I am getting a compile error: error: ‘leds’ was not declared in this scope

Specifically I think I am not including struct CRGB leds[NUM_LEDS] in the right place now.

Does it go in the .cpp file, the main sketch or inside the class in the .h file?

2

If your declaration of CRGB leds[NUM_LEDS]; is in the main sketch, your other files can include the line extern CRGB *leds; to reference that same piece of memory.

3

Great, and that just goes outside of any class code?

4

Put it near the top of any .C or .CPP file that references it.

Technical details: In C++ parlance, this is called a “forward declaration”. With the addition of the extern qualifier, this instructs the compiler to ignore the fact that the actual declaration is not in the current file.

5

Do I do something similar for the #defines as well?

#define LED_PIN 2
#define NUM_LEDS 50
#define BRIGHTNESS 100

6

I’ve been testing and it seems I have to include the #define statements in the main sketch and in the cpp files to get it to work. Is that right?

7

I’m really struggling to work out how to use FastLED inside an object. Are there any good examples of how this can be done simply, even a blink example?

8

OK so at the moment I have this in the header:

#define NUM_LEDS 50
#define LED_PIN 2
#define BRIGHTNESS 25

and

struct CRGB leds[NUM_LEDS];

in the .cpp

I would like to move the #defines to the main sketch is possible so they are more global as I will be introducing more classes further down the line.

Can I use references or pointers to the #defines?

9

@Luminous_Elements I tried using extern CRGB *leds; in the cpp file for my object and it compiles with no errors but the sketch doesn’t work. Is that really all I need to do, or should I also be changing how the other parts of the code referend leds ?

10

@Luminous_Elements I got it to work by using extern struct CRGB leds[]; without the forward declaration, but I think this might cause further problems down the line when I use it multiple classes