WS2812 RGB and/or SK6812 RGBW flame effects?

David Betz

Has anyone written any code to simulate flickering flame light using RGB or RGBW LEDs? I don't need the effect to look like a flame when viewed directly, just produce light that looks like a fire when reflected off of a wall.

xanadu

I have some RGBW on the way to test out JM's new driver.

I thinking about connecting a CdS cell to an ADC and recording a real flame. Add some randomize to that pattern and see how it looks.

David Betz

I found this: http://www.walltech.cc/neopixel-fire-effect/

Looks like a pretty good flame effect. I made an attempt to convert his code to Spin and got this:

var
    long seed

con
    r = 255
    g = r - 40
    b = 40
    
pub flame(buf, len) | flicker, r1, g1, b1, x
    repeat x from 0 to len - 1
        flicker := ?seed // 150
        r1 := r - flicker
        g1 := g - flicker
        b1 := b - flicker
        if r1 < 0
            r1 := 0
        if g1 < 0
            g1 := 0
        if b1 < 0
            b1 := 0
        long[buf][x] := (r1 << 24) | (g1 << 16) | (b1 << 8)
    time.pause(50 + (||?seed // 100))

It seems to work although the color temperature isn't quite right.

xanadu

Nice, I will revisit when the hardware comes in.

David Betz

Here is an update to the flicker code that seems to work a bit better. It is based on the code here: https://github.com/danesparza/Halloweenfire

var
    long seed

con
    r = 226
    g = 121
    b = 35
    
pub flame(buf, len) | flicker, r1, g1, b1, x

    repeat x from 0 to len - 1
        flicker := ||(?seed // 55)
        r1 := r - flicker
        g1 := g - flicker
        b1 := b - flicker
        if r1 < 0
            r1 := 0
        if g1 < 0
            g1 := 0
        if b1 < 0
            b1 := 0
        long[buf][x] := (r1 << 24) | (g1 << 16) | (b1 << 8)
        
    time.pause(10 + ||(?seed // 103))

Edit: I should mention that I've been using JonnyMac's jm_rgbx_pixel.spin driver.