Lately, I've had a lot of free time on my hands, so I've been working on a bunch of projects.

This project will allow you to control RGB LEDs via Google Home using a Raspberry Pi. Now there are 3 parts of the project, setting up a Raspberry Pi, setting up Google Home with a custom command using IFTTT, and then creating a circuit for the lights. I made the circuit myself, but I bet you could get something from Adafruit that does what is needed.

Materials for Raspberry Pi Part

Raspberry Pi - any will work, but I'm using a Zero
Wireless Dongle - if the Pi doesn't have built in Wifi
Google Home - Optional if you have Google Assistant on your phone

Materials for Circuit Part- Don't let this deter you... It's fairly simple

Protoboard
Wire
LED Strip
12V Power Supply - Anything above 2 Amps should be fine
DC Barrel Jack - Same size as your power supply's
NPN BJT Power Transistors (x3) - I'm using TIP31C
Male & Female Pin Headers - Optional, but highly recommended

Step 1: Downloading Express for the Pi

I'm not going to go into too much detail about setting up the Pi because there are so many tutorials out there for setting them up.

What you'll need to do that I'm not covering...

Flashing Raspberry Pi with newest Raspbian
Setup the network card so you can access the internet from the Pi
Set a static IP on the Raspberry Pi

Now here is where the fun begins! We need to install nodeJS, npm, express, and express-generator.

sudo apt-get update
sudo apt-get install nodejs npm

Once those are installed, run the following

npm install express express-generator

Express allows you to make a very basic webserver for your Raspberry Pi to use. Express-generator just auto generates files for an express server.

Make a directory and cd into the directory. I named mine piWebpage. Now run the following (seen in the picture too)

mkdir piWebpage
cd piWebpage
express --view=ejs webApp

This will generate a folder named webApp with all the express files in it. If you plan to do more with this webpage later and you like PUG, replace --view=ejs with --view=pug. We won't be touching the webpage, so for this application, it doesn't matter what we use.

Step 2: Pi Server Setup

Move into the new webApp directory.

cd webApp
npm install

npm install will take some time because it is installing all the dependencies for express.

Paste setColor.py into the webApp folder. This file has some presets in it for basic colors. Feel free to add more as you like. The range is 0 to 255 where 255 is full color. At some point, I will likely add the ability to dim the lights, but for now, they are full brightness.

Move into routes

cd routes

Now replace index.js with the file attached. This will add some lines to receive a POST command which is what the Google Home will send. From that POST, we will get the color selected and tell the Pi to run the setColor python script to adjust the lights.

One last thing... Go back to webApp folder.

cd ~/piWebpage/webApp

Using your favorite editor, paste and save the code below into your webApp.js. Anywhere is fine as long as it is before "module.exports = app;"

// Setup LED hardware driver
const {exec} = require('child_process');
exec('sudo pigpiod',(err,stdout,stderr)=>{
  if(err){
    console.log('Error loading LED Driver');
    return;
  }else
    console.log('LED Driver Successfully Loaded');
});

Like the comment says, pigpiod is the hardware driver for PWM signals that we will use to adjust the LED colors. I believe it comes already installed in Raspbian, but if not...

sudo apt-get install pigpiod

Now for the real test! Starting the server!

DEBUG=webapp:* npm start

Step 3: IFTTT Setup (Trigger)

IFTTT can do a lot, and I would highly recommend looking around at some of the applications.

First, you'll need to make an account. Use the same Google account associated to your Google Home, otherwise they won't sync together. Once complete and logged in, click the upper right of the IFTTT page where it shows your name and avatar. Then click New Applet from the dropdown.

If you're curious, IFTTT stands for IF This Then That if you didn't notice by the screen that pops up. So what we want is If Google Assistant, then Webhook as our options.

Proceed by clicking +this which will load a search bar. In the search, type Google Assistant and click the icon below the search.

In Choose a Trigger, select the 3rd option called Say a phrase with a text ingredient. Now this allows you to have 3 commands that will do the same action. You add the $ into phrase where you would mention the color. For example, if I naturally would say Hey Google, Set LEDs Blue (as natural as yelling at a device can be), then I would type into the field Set LEDs $. Do that for all 3 fields with different versions of the command.

The 3 I used were

LEDs $

Set LEDs $

Set LED color $

The last field is what you would like your Google Home to reply after saying your command. It can be anything you want, but I used Setting color to $. The $ means she will repeat the color back.

Click Create Trigger

Step 4: IFTTT Setup (Action)

After clicking Create Trigger, you'll load back to the if this then that view, but this has been replaced with the Google Assistant logo. Proceed by clicking +that

Same thing as before where it brings you to the search bar. Type in Webhooks and click the webhook icon below the search bar. Under Choose Action for Webhooks, there is only one option, so click Make a web request.

Here is where things get a little tricky. Because Google isn't another computer in your house, you'll need your external IP address. This will require some port forwarding, but we will touch on that later. To get your external IP address, go to https://canyouseeme.org/

In the URL field, type http://xxx.xxx.xxx.xxx:3000/{{TextField}} (with the x's being your external IP address). In case you're curious, TextField will have the color you selected when you make a command. The reason we use 3000 is because that is the port the Raspberry Pi Express server is running on. (You can change the port in the code, but we are just using the default settings for Express)

For Method, select POST.

For Content Type, select text/plain.

For Body, type in {{TextField}}

Those of you that know how a POST command works, you would think that if you parse the body property of the request that you would get the color. For some reason, nothing is ever put into the body field of the request, so I'm actually parsing the URL for the color. Hope that gets fixed soon, as that would simplify my code in the index.js route. But I digress.

Lastly, click Create Action and then Finish on the next page. (I turned off notifications, but that's preference)

Step 5: Port Forwarding

This is where things get difficult to explain because all routers are different...

Now we have Google sending a command to our house using port 3000, but it doesn't know which device on the LAN it needs to go to. To remedy this, we need to forward port 3000 to the local IP address of your Raspberry Pi.

Go into your router using either 10.0.0.1 or 192.168.1.1 (I've also seen it where the last digit is 254) and find port forwarding. In port forwarding, similar to the image, you'll name a new device (IFTTT) and forward the port (3000) to the Pi's IP address (in my case 10.0.0.11).

Save your new setting, reboot your router, and check to make sure your Raspberry Pi server is still running. If it isn't running, start it up again.

Go back to that handy website https://canyouseeme.org/. Below your IP address, it has a port checker. Assuming your port forwarding is correct, type in 3000 and hit check port. It should come back with a Success.

Step 6: Checking Your Work So Far

Now... the moment you've been waiting for... Tell Google a command such as LEDs blue (if you followed my example).

Assuming all went correctly, you'll get the output seen in the picture. We don't have a circuit yet, so all you'll see is text on a screen. There is usually a second or 2 delay before it is processed from Google and appears on the Pi.

(Skip to next step if this came out similarly to the picture)

Now there are a few things to look at if it didn't work...

In the picture, there is a line that says

POST /color/blue 200 250.458 ms - 2

The 200 is the important part. If you are not seeing a 200, then there was a bad POST meaning your server didn't know what to do with the data. Go back to Step 2 and check your index.js file.

Also in the picture

stdout: blue
stderr:

This is the output from the python file that runs the LEDs. If you see an error there, it might be that you don't have the driver installed on Step 2.

Lastly, if nothing showed up at all... your IFTTT might not have been setup correctly or failed to connect to the server. Go back to the IFTTT page, and in the top nav bar, click Activity. In there, you can see every time your app has run, and if there was an error, you can see what it was. I made a Google command with the Pi server off and got the error in the picture.

Step 7: Building the Circuit

The reason why we need to do this is because the Raspberry Pi don't have enough power... So the solution is... MORE POWER (Tim the tool man Taylor grunts in the distance). AKA another power supply (12V 2A)

Materials for Circuit Part

Protoboard
Wire
RGB LED Strip
12V Power Supply - Anything above 2 Amps should be fine
DC Barrel Jack - Same size as your power supply's
NPN BJT Power Transistors (x3) - I'm using TIP31C
Male & Female Pin Headers

Using the handy picture I stole from the interwebs with the GPIO of the Pi Zero, you can see GPIO17, GPIO18, and GPIO 27 are all right next to each other with a GND. We will be using that square of 4 pins (Pins 11, 12, 13, 14).

First off, I would recommend soldering male headers onto your LED strip as seen in the image (not my best work). This allows for an easy disconnect if you ever need to. I used female headers for the connection of the LED strip to my protoboard and male headers from the protoboard to the Raspberry Pi. (Always use female connections for power/signal source). You don't need to move all of the Pi's pins all next to each other like I did... I just wanted it to look clean, but it was a lot of work.

Circuit Explanation

For those of you unfamiliar with transistors, transistors are basically a digital switch. The GPIO pins from the Pi trigger the three switches (red, green, and blue). Looking specifically at RED in the circuit diagram, when GPIO_17 is on, the switch "closes" connecting RED to GND causing the red lights to turn on. When GPIO_17 turns off, then the switch is open and thus the lights are off.

Base - GPIOs

Collector - Colors (RED, GREEN, BLUE)

Emitter - Ground (of both the Power Supply and Pi)

Make sure to connect the Pi's ground to the ground of the power supply. The lights will still work, but they will appear very dim until the ground is connected.

I have a 4th transistor looking device on my protoboard. It is a L7805CV which is used to convert 12V to 5V so I could power the Pi on the same circuit. It worked but kept over heating, so I removed it's connections.

Step 8: Test It Out!

Once complete with the circuit, restart your Pi before making any connections. This is because the pins are probably still active from the server test. Alternatively, you can kill the server and the pigpiod service.

Plug in the LEDs and the jumpers from the protoboard to the Pi. Double check all connections before providing power. If you wired it wrong, you might fry your Pi (no pressure).

Checklist