Christmas Lights with Raspberry Pi and GPIOZERO

We were in Wilco yesterday and spotted some battery powered LED xmas lights for the bargain price of £2.50. They seemed ideal for a bit of festive hacking

There were a few types available and I picked up 3 different ones: warm white LEDs on a flexible but fairly rigid wire, some brighter white LEDs encapsulated in a snowflake housing and some traditional multi-colour LEDs.

The strings of LEDs come attached to  two AA cells in a neat enclosure with an on/off switch. I snipped the wires fitted jumper wire housings to the end of each so I could plug them straight onto the GPIO header. As the LEDs run on 3v and I was intending to drive them using an 'expendable' model B, I decided not to bother with a series resistor. 

I kept the batteries and the holders - these are bound to be useful for other projects (similar boxes can cost almost as much as the whole LED set).

Then I knocked up a quick Python program to run a mixed illuminate sequence for each of the lights. 

from gpiozero import PWMLED

from time import sleep

import random

import threading

white = PWMLED(23)

snowflakes = PWMLED(18)

colours = PWMLED(25)

LIGHTS = [white,snowflakes,colours]

def gentle(lights):

    for x in range(1,100):

        lights.value = x/100

        sleep(0.05)

def randomblink(lights): 

    lights.blink(random.randint(1,10)/10,random.randint(1,10)/10,10,False)

def sequence(lights):

    while True:

        print('gentle')

        gentle(lights)

        print('sleep')

        sleep(random.randint(1,10)/10)

        print('blink')

        randomblink(lights)

        print('sleep')

        sleep(random.randint(1,10)/10)

        print('on')

        lights.on()

        print('sleep')

        sleep(random.randint(1,10))

for i in LIGHTS:

    t = threading.Thread(target=sequence, args=(i,))

    t.start()

I then added a line to the /etc/rc.local file on the Pi so that the Python code runs automatically at startup.

Our Christmas tree was already quite covered with decorations so I decided to use these new lights on our spiky cactus!