@livius Thanks! I couldn't figure it out (quite new to python).. Ended up with this: def rgb_to_hex(red, green, blue): """Return color as #rrggbb for the given color values.""" return '%02x%02x%02x' % (red, green, blue) for i in range(256): color = rgb_to_hex(i,i,i) pycom.rgbled(256-int(color,16)) time.sleep(0.005) This just fades from white to off, removing the '256' fades from off to white.. Probably not the smoothest way to do it, but it works. :)