For my Raspberry Pi powered jack-o'-lantern

spooky.jl

using SenseHat
import SenseHat: RGB565

function spooky(decay, arriv, refresh)
    x = rand()
    while true
        x *= exp(-decay*refresh)
        if rand() < arriv*refresh
            x += (1-x)*rand()
        end
        led_display([RGB565(x,0,0) for i = 1:8, j = 1:8])
    end
    sleep(refresh)
end

spooky(0.2,0.1,0.01)