#Define，NeoPIxel的RGB颜色

Question

Am playing with the NeoPixels on the Particle Photon. Have got example code up an running which spins the neopixels through different colors. However a little confused on how to extend this, particularly with the way it has defined the neopixel colors.

The sketch defines the colors as so

#define BLUE 5,5,190
#define WHITE 150,150,150
#define GREEN 10,180,10

and calls the following function Spin in this fashion

spin (BLUE);

void spin(int R, int G, int B) {
     for(i=0; i < PIXEL_COUNT; i++) {
         strip.setPixelColor(i, R,G,B);
         strip.show();
         delay(waitTime);
     }
     for(i=0; i < PIXEL_COUNT; i++) {
         strip.setPixelColor(i, 0,0,0);
         strip.show();
         delay(waitTime);
     }
 }

I want to send the Photon commands to change the color, so need to set a variable equal to one of the defined colors and pass to the spin function. However, setting the variable to Int fails ie

int lightcolor = BLUE;

I have also tried an array

int lightcolor [] = BLUE;

this fails as well.

i managed to get int lightcolor [1,1,1] = BLUE

to pass the compiler, but it failed on the functional call

spin(lightcolor)

or spin(lightcolor[1,1,1]}

just not sure what I am missing here with regard to how the #define declares that const and how to use it throughout the sketch

thanks

Answer 1

You should look up what a define statement actually is. The preprocessor will replace BLUE with the characters 5,5,190 in the source file before the compiler even sees it.

Thus, spin(BLUE) works because spin(5,5,190) works. If you want to assign BLUE to a variable, you actually have to assign it to three variables because spin takes three independent variables, one for each color channel. Why even assign to a variable anyway? Why not use the define?

Read an intro to c or c++ (they're different languages) and learn what you're doing. Poking around blindly like you're doing is unlikely to produce good results.