PiRGBLed.py

import pigpio
from math import pi, sin
from time import sleep

class RGBLed(object):
	def __init__(self, r_pin=22, g_pin=23, b_pin=24):
		self.__pins = (r_pin, g_pin, b_pin)
		self.__pi = pigpio.pi()

	def __call__(self, r, g, b):
		rgb = (min(255, max(0, int(i))) for i in (r, g, b))
		for val, pin in zip(rgb, self.__pins):
			self.__pi.set_PWM_dutycycle(pin, val)

	def police(self, T, n=40, cycles=None, offset=0, brightness=255):
		while cycles is None or cycles > 0:
			for i in range(n):
				value = sin(float(i)/n*2*pi + offset)*brightness
				blue = value if value > 0 else 0
				red = -value if value < 0 else 0
				self(red, 0, blue)
				sleep(float(T)/n)
			if cycles is not None:
				cycles -= 1

	def strobe(self, f, cycles=None, r=255, g=255, b=255):
		while cycles is None or cycles > 0:
			T=1.0/f;
			for vals in [(r, g, b,), (0, 0, 0,)]:
				self(*vals)
				sleep(float(T)/2)
			if cycles is not None:
				cycles -= 1

if __name__ == "__main__":
	from argparse import ArgumentParser

	parser = ArgumentParser(description="Control RGB led with Raspberry Pi")

	for i in ["Red", "Green", "Blue"]:
		parser.add_argument(i, type=int, nargs='?', default=0, help="Value for " + i[0] + ", should be 0 <= " + i[0] + " <= 255")
	parser.add_argument("--pins", type=int, default=(22,23,24), nargs=3, metavar=("R","G","B"), help="Pin numbers for R, G, and B")
	parser.add_argument("--police", action="store_true", help="Flash alternatively red and blue")
	parser.add_argument("--strobe", action="store_true", help="Flash white repetitively")
	args = parser.parse_args()
	set_rgb = RGBLed(*args.pins)
	try:
		if args.police:
			set_rgb.police(2)
		if args.strobe:
			set_rgb.strobe(20)
	except KeyboardInterrupt:
		pass
	set_rgb(args.Red, args.Green, args.Blue)

PiTwoLedPolice.py

from argparse import ArgumentParser
from threading import Thread
from time import sleep

from PiRGBLed import RGBLed

def police_cycle(led, T=2, n=20, b=255):
	while True:
		led.police(T=T, n=n, cycles=3, brightness=b)
		led.strobe(f=1/(T/32), cycles=8, r=b, g=b, b=b)

parser = ArgumentParser()
parser.add_argument("--cycle-time", "-T", type=float, default=2.0)
parser.add_argument("--num-steps", "-n", type=int, default=20)
parser.add_argument("--brightness", "-b", type=int, default=255)
args = parser.parse_args()

threads = []
leds = [RGBLed(17,18,19), RGBLed(22,23,24)]
for led in leds:
	threads.append(Thread(target=police_cycle, args=[led, args.cycle_time, args.num_steps, args.brightness]))
	threads[-1].start()
	sleep(args.cycle_time/4)

try:
	for thread in threads:
		thread.join()
except KeyboardInterrupt:
	pass

for led in leds:
	led(0,0,0)