Christmas is a very special time of year for me and my family. Every year, we celebrate the holidays by making a project together and it becomes a memory for me and my wife.
Having moved across the continent, this year's project is one that is on a budget. I started by procuring items from the dollar store and with a handful of components that I brought with me, my wife, my son and I set out to build a mini Christmas festival. I will be keeping the explanation brief though the discussion can be a lengthy one.
Our project consists of 2 parts which are intended to serve two different purposes. The first part is designed with the Raspberry Pi at the centre and Texas Instruments BLE lights as the end devices along with a sense hat for good measure. Python based web app allows for the control of colours for the budget tree as well as the jolly snowman.
The second part employs two BBC:Micro bits talking to each other wirelessly and are allow for the control of a string of lights and a musical house.
Take a look at the video and then we can walk through the construction.
Video
The Python Server
The Texas Instruments BLE lights can be connected to via a number of methods. I wrote about talking to them via NodeJS over at HackADay making them IoT Lights and wanted to challenge myself to use python instead.
Here is a basic block diagram of the plan.
Working
The Raspberry Pi 3 runs a Python Flask Server that does two things.
1. It serves up html/css/js files that are requested by a web browser. The loaded page contains a GUI with coloraturas pickers as well as action buttons. The page is also loaded with a javascript element that allows coloraturas picker data to be sent via simple REST like call to the python server.
2. The Flask server also exposes a REST like API that allows a client to select a light and send it coloraturas data
Once the web page is loaded, the user can use a coloraturas picker for a particular light. Once the user make a selection, a REST call is trigged and the RGB data is sent to the Flask server. This is translated from text to hex values and passed onto the Bluetooth LE module.
The Bluetooth LE module is also written in python and allows for the scanning and then communication with BLE lights. The UUIDs are made part of the module and hence once the RGB values are passed to it, it scans for BLE light presence. If found, it then updates the BLE light's characteristics thereby changing the light.
There are a number of components to this and the code is flexible enough to allow future expansion. I also added an animation function that sends varying RGB data to the lights making them change colour in sync with each other.
Dollar stuff
Both the tree and snowman are dollar store bought outs and I implanted the LED lights to make things work. Neo-Pixel strip are way too expensive for us right now and would also require an external power source. I did get an RGB LED strip from Peter Sir but buying an SMPS, LED driver, PCB etc etc was not in my budget this year.
BBC Micro bit remotes
My son is almost three and he loves to play around with machines and buttons. I wanted to give him the ability to interact with the Christmas project and hence I opted for the wireless control.
Working
One of the Microbits have the pins broken out and I used 2N3904 NPN Transistors as switched to turn ON and OFF two things. First was an LED strip which was procured at the dollar store and the LEDs change colour due to their internal circuitry.
Second, is a small house with a music chip that plays the Christmas carols which was perfect. After hacking it open, I connected the transistor and resistor directly to the contact.
The code sends commands to toggle the GPIOs ON and OFF and the state is saved within the remote itself.
I also employ the LED matrix to display a merry Xmas once the microbit is glued atop the small house.
One button allows for toggling the lights while the other button allows for control over the music (and message board).
I could have easily connected the Microbit to the Raspberry Pi by the use of GPIOs.
Model Construction (on a budget)
Water colours can and will bring out the child in everyone and my better half was more than happy to create a model. Cotton for snow and just paint and crayons made this project a family effort. After all its all about bringing everyone together. 
Some Christmas toothpicks and ornaments later, we had a small village with Santa Clause, reindeers and a cottage. My son added his collection of Paw Patrol pups and I added a Lego Anakin Skywalker with R2D2. Everyone had a lot of fun
The code
Yes the entire code is up on GitHub and you can download and modify as you like. I am learning better python and hence packaging things was something new.
Head on over to http://github.com/inderpreet/py_e14_holiday_lights_and_music
I am yet to do a setup script though manually installing the modules is quite simple.
"""
@file bbc_recieve
@brief BBC microbit Receiver By Inderpreet Singh
"""
import radio
import random
from microbit import display, Image, button_a, sleep
radio.on()
def mOn():
pin0.write_digital(1)
def mOff():
pin0.write_digital(0)
def lOn():
pin1.write_digital(1)
def lOff():
pin1.write_digital(0)
# Event loop.
while True:
# Incomming
incoming = radio.receive()
if incoming == 'm-on':
mOn()
elif incoming == 'm-off':
mOff()
elif incoming =='l-on':
lOn()
elif incoming = 'l-off':
lOff()
"""
@file bbc_tx
@brief BBC microbit Receiver By Inderpreet Singh
"""
import radio
import random
from microbit import * #import display, Image, button_a, sleep, button_b,
music = False
lights = False
shake = False
count = 0
radio.on()
def toggleMusic():
global music
if music == False:
music = True
radio.send('m-on')
elif music == True:
music = False
radio.send('m-off')
def toggleLights():
global lights
if lights == False:
lights=True
radio.send('l-on')
elif lights == True:
lights = False
radio.send('l-off')
# Event loop.
while True:
if button_a.was_pressed():
toggleMusic()
if button_b.was_pressed():
toggleLights()
if accelerometer.was_gesture('shake') and shake == False:
lights = True
music = True
radio.send('l-on')
radio.send('m-on')
shake = True
count = 30
sleep(1)
if shake == True:
count = count - 1
if count == 0:
lights = False
music = False
radio.send('l-off')
radio.send('m-off')
shake = False
sleep(1)
Conclusion
Christmas is all about family and I a feel these projects have become a tradition for us. We did the best we could given the limited resources and budget I have this year and I am hoping my son will be an active participant next year. I ventured into Python for this project and learned about creating a web server as well as implementing a REST API. I also got the chance to put the BBC Microbit in the hands of my son and I am hoping this will escalate.
I hope you had as much fun watching and reading as we had making it. Thanks again and belated happy holidays.
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