LED strip library: fading

[tobiaszehntner]

Hey there,

I have a problem making my LEDs fade individually. The problem is that the library that controls the strip only allows brightness values for RBG 0-255, and if it goes over that, it will loop back to 0.

This means that the following code never gets into the second if-loop to have goingUp become false.

if(goingUp[i])
            {
              ledPos[i].r += fadeRate;
              ledPos[i].g += fadeRate;
              ledPos[i].b += fadeRate;

                 if(ledPos[i].r > 255)
                 {       
                   goingUp[i] = false;
                 }              
            } else
            {
              ledPos[i].r -= fadeRate;
              ledPos[i].g -= fadeRate;
              ledPos[i].b -= fadeRate;
            }

Now I could set it to >250. However, if fadeRate = 20 it would go from 240 back to 0 before reaching goingUp[i] = false, because the library doesn't allow it to go over 255. Is there a smart way to go around that while still being able to have a variable fadeRate?

Thanks,
Tobias

[bakercp]

Perhaps consider the modulo operator ... ?

[mikewesthad]

If I understand this correctly, your rate variable is just being added/subtracted each time loop is called?

How about this?

if(goingUp[i])
{
    if(ledPos[i].r + fadeRate > 255)
    {       
        goingUp[i] = false;
        // Set your leds to the maximum brightness here if you like
    } 
    else {
        ledPos[i].r += fadeRate;
        ledPos[i].g += fadeRate;
        ledPos[i].b += fadeRate;
    }
}
else 
{
// Do a similar operation but with -fadeRate
}

...

[tobiaszehntner]

The modulo still messes with my brain, so I went with Mike's suggestion. Works like a charm, thanks!

[bakercp]

nice. ... but ... you will not regret mastering the modulus!