apa102 demonstration on nodemcu

apa102.lua

start_frame = string.char(
	0x00, 0x00, 0x00, 0x00
)
end_frame = string.char(
	0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff,
	0xff, 0xff, 0xff, 0xff
)

--color order is BGR

rainbow_pattern = string.char(
	0xff, 0x00, 0x00, 0xff,
	0xff, 0x00, 0xbb, 0xdd,
	0xff, 0x00, 0xdd, 0xbb,
	0xff, 0x00, 0xff, 0x00,
	0xff, 0xbb, 0xdd, 0x00,
	0xff, 0xdd, 0xbb, 0x00,
	0xff, 0xff, 0x00, 0x00,
	0xff, 0xdd, 0x00, 0xbb,
	0xff, 0xbb, 0x00, 0xdd
)

rainbow_count = string.len(rainbow_pattern)

led_count = 150

pin=8 
spi.setup(1, spi.MASTER, spi.CPOL_LOW, spi.CPHA_LOW, spi.DATABITS_8, 0);
gpio.mode(pin, gpio.OUTPUT)

rainbows = (led_count * 4) / rainbow_count
partial_rainbow = rainbows % 1;

print(
	spi.send(
		1,
		start_frame..string.rep(
			rainbow_pattern,
			rainbows - partial_rainbow
		)..string.sub(
			rainbow_pattern,
			1,
			partial_rainbow * rainbow_count
		)..end_frame
	)
);