Hello,  I am having a hard time getting the HSV function to work.

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1

Hello,

I am having a hard time getting the HSV function to work.

i have tried

leds[i].setHSV(0,255,255);

I would expect a bright red, but the strip doesn’t light.

if i do

leds[i].setRGB( 255, 0, 0);

i get the bright red…

I am using the latest version of FastLED, do i need to have some other library imported besides fastLED.h?

2

Try
leds[i] = CHSV( hue, sat, value);

That work better?

3

This is how I use the CHSV function:
for(byte i = 0; i < NUM_LEDS; i++){
leds[i] = CHSV(0,255,255);
}

4

that doesnt seem to work. Does anyone have any example code with this working?

5

Lots of code uses this and works fine. I’m suspecting a configuration issue.

What version of FastLED are you using? And what happens on your strip when you use that syntax? Last thing: could you post your entire code to pastebin (or similar) so we can help track down the issue?

6

Yes, it was was another one of those user errors…

my for loop was messed up. I had

for(byte i; i < NUM_LEDS; i++){
leds[i] = CHSV(0,255,255);
}

as soon as i changed it to

for(byte i = 0; i < NUM_LEDS; i++){
leds[i] = CHSV(0,255,255);
}

worked fine. Im new to programming, but i thought every time you declared a variable, it was set to zero?

7

Ah! In C and C++, the initial value of all variables is undefined, so always initialize everything.

8

Problems with this can wind up being security holes in production software; it even has a special designation code: CWE-457 “Use of Uninitialized Variable” http://cwe.mitre.org/data/definitions/457.html

(Not that this matters in the FastLED context, but Dan and I work together in the computer security industry, so it comes to mind automatically!)