#!/usr/bin/env python3
import serial
import time

DEVICE = "/dev/ttyUSB0"
BAUD = 250000         # DMX baud
CHANNELS = 512
ACTIVE_COUNT = 24     # cycle through channels 1..24

def send_dmx(ser, data):
    try:
        ser.break_condition = True
        time.sleep(0.0001)           # 100 µs
        ser.break_condition = False
    except Exception:
        ser.baudrate = 57600
        ser.write(b'\x00')
        ser.flush()
        ser.baudrate = BAUD

    time.sleep(0.000012)  # 12 µs MAB
    frame = bytes([0x00]) + bytes(data)
    ser.write(frame)
    ser.flush()

def main():
    dmx_values = bytearray([0]*(CHANNELS))  # index 0 -> channel 1
    with serial.Serial(DEVICE, baudrate=BAUD, bytesize=serial.EIGHTBITS,
                       parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_TWO,
                       timeout=1) as ser:
        time.sleep(0.1)
        chan = 0
        try:
            while True:
                # clear all
                for i in range(CHANNELS):
                    dmx_values[i] = 0
                # set active channel (channels 1..ACTIVE_COUNT)
                dmx_values[chan] = 255
                send_dmx(ser, dmx_values)
                time.sleep(0.025)  # frame delay; adjust if desired

                # advance channel (wrap within 0..ACTIVE_COUNT-1)
                chan += 1
                if chan >= ACTIVE_COUNT:
                    chan = 0
        except KeyboardInterrupt:
            pass

if __name__ == "__main__":
    main()