import machine
import neopixel
import time
import framebuf as fb

NR_PIXEL_WIDTH = const(8)
NR_PIXEL_HEIGHT = const(8)
buf_array = bytearray(NR_PIXEL_WIDTH * NR_PIXEL_HEIGHT * 3)

p1 = machine.Pin(13,machine.Pin.OUT)
fbuf = fb.FrameBuffer(buf_array, NR_PIXEL_WIDTH, NR_PIXEL_HEIGHT, fb.RGB888)

@micropython.viper
def zickzack_rgb24(fbuf):
    buf = ptr8(fbuf)
    for y in range(0, NR_PIXEL_HEIGHT, 2):
        offset_s = NR_PIXEL_WIDTH * y * 3
        offset_e = offset_s + 3 * (NR_PIXEL_WIDTH - 1)
        # print("{} - {}".format(offset_s, offset_e))
        for x in range(0, NR_PIXEL_WIDTH//2):
            tmp = buf[offset_e - x * 3]
            buf[offset_e - x * 3] =  buf[offset_s + x * 3]
            buf[offset_s + x * 3] = tmp
            tmp = buf[offset_e - x * 3 +1]
            buf[offset_e-x * 3 + 1] =  buf[offset_s + x * 3 +1]
            buf[offset_s+x * 3 + 1] = tmp
            tmp = buf[offset_e - x * 3 +2]
            buf[offset_e - x * 3 + 2] =  buf[offset_s + x * 3 + 2]
            buf[offset_s+x * 3 + 2] = tmp

def write_neo(text):
    fbuf.fill(0)
    for c in text:
        fbuf.text(c, 0, 0, 10)
        zickzack_rgb24(buf_array)
        neopixel.neopixel_write(p1, buf_array, 1)
        time.sleep(1)
        fbuf.fill(0)

write_neo("HALLO")