Creating Your Own Smart Outlets for Cheap

I've started to spend a little time learning about how to make my own basic electronic hardware as I delve into some simple home automation. One of the things that struck me, at least at the time of this writing, was that wifi outlets are still $25/each (which is cheaper than they were before, but in my opinion, still too expensive to be valuable).

A while ago I picked up Etekcity wireless outlets, which come with a remote controller and work on the RF frequency. I had intended to automate these, but recently I got a Google Home, which pushed me to take another shot.

Warning

There are plenty of risks when working with electricity. I am not responsible for fires, explosions, or electrocutions you may encounter while creating your circuit. My post is my personal learnings, which may be flawed, missing information, or non-reproducible. Be careful, and do so at your own risk.

The Parts

Hardware

• Etekcity Wireless Outlets: 5 pack ($25)
• 433 Mhz Rf Transmitter/Receiver ($6)
• Particle Photon $20
• Basic random parts (Breadboard, and some wires). I had one already, but you should be able to pick one up for $5-10 from Amazon

Total price: $55 (for 5 outlets)

I actually had a Spark Core, but the Photon is a newer version, and should work just fine.

Software

I was able to use Particle's Web-IDE on their website. I created a new program for my Particle, and added the RCSwitch library straight from their IDE.

You will also need the particle-cli. I used this for both first-time-setup, as well as connecting to the particle's serial device.

Security Notes

I feel obligated to at least leave a short note here: These RF lights work similar to an old garage door opener, meaning that anyone can listen for the codes, and turn on/off whatever you hook up the outlets to. Personally, if someone turns off a light that doesn't bother me much, but it's something to keep in mind before you hook it up to your TV.

Hardware Circuit

Diagram

I used Fritzing to create the below sketch.

IMPORTANT: Please be careful to make sure you connect the right pins on your RF receiver to the right data pins. I made this diagram based on the parts available in the application, which may or may not match the parts you purchased (They don't match my parts below).

The important bits is to connect:

• VCC to VIN pin on the particle
• GND to GND
• Transmitter data pin to D4 (Or change the code)
• Receiver data pin to D1 (Or change the code)

End-Result

The actual end-result. There's some extra wires on here because I also hooked up a temperature sensor:

The Code

Explanation

The code has a few different parts that you should pay attention to:

• Make sure inputPin and transmitPin are set according to how you attached the RF chips to your particle.
• Uncomment #define RECEIVER to allow receiving code to run, same with TRANSMITTER
• You'll need to set up your lights variable to be the name, the on-code, and the off-code. We'll cover this below.

Code

Difficulties

I ran into a few different problems, most of which I suspect is a result of using an older version of the Particle Photon:

• You need to enable interrupts by calling interrupts() before setting up the RCSwitch Library
• In the RCSwitch library, you always need to call setPulseLength after setProtocol, because the latter will override the former
• I also updated the firmware of my spark core to 0.6.1, but again, I had old hardware

Setting it all up

Make sure to follow Particle's instructions for setting up your Photon with your account prior to these instructions.

Step 1: Capture RF Codes

The first step we'll need to do is capture the RF codes from our remote so we can add the codes to the configuration.

Steps:

1. Uncomment #define RECEIVER to enable receiver functionality
2. Plug in your particle to your computer, and publish the code to your particle
3. From a terminal run particle serial monitor. This will connect the terminal to your particle and output RF codes
4. Hold your remote near the device, and press the codes. Write down the RF codes and which button they map to

Step 2: Configure the code to use your RF Codes

After you have all the RF codes, all you need to do is set up the lights configuration variable in the code!

If you have a set of 3 lights, it should look like this:

const LIGHT* lights[] = {
    //lightDef("name", <on code>, <off code>),
    lightDef("light1", 267571, 267580),
    lightDef("light2", 267715, 267724),
    lightDef("light3", 268035, 268044)
};

Step 3: Try it out with particle's console

In the particle console you'll be able to see your device. There, you should be able to call the function lights that the particle exposes. Here, you can specify it an argument, which will tell the particle which RF codes to send.

It exposes a single function, where you can send an encoded string. The first character is a code, followed by light ids:

Code:
  a - activate
  d - deactivte
eg:
  a12 - activate lights 1 and 2
  d1 - deactivate light 1
  a1d23 - activate light 1, and deactivate 2 and 3
  aall/dall - activate/deactivate all
  alight1 - activate light with name "light1"
  dbed - deactivate light named "bed"

Step 4: Set up with website, or voice assistant

Of course, this is optional, but it's also fun! I used IFTTT, which turned out to be very convenient because it has direct integration to the Particle! This allows me to hook up its app, or Google Assistant, very easily to call the exposed function on the particle.

You can do all sorts of things with IFTTT, from emails, to calls, to location tracking (eg, automatically turn on all your lights when you arrive home).

Particle also has their cloud API which allows you to call functions on your particle easily by calling their API. I've written some custom mobile UIs using this API.

Conclusion

This was a fun experience for me, but it also took much longer to figure out than I care to admit. Hopefully this article helps you in your own home automation projects!