IoT Introduction: Smart Plugs

In the world of home automation, I am seeing more and more product options and use cases. There's a common phrase in personal organization: eliminate, automate, or delegate, and having kids in the home I find myself needing every second to count by the end of the day. I bought a pack of four Kasa Smart Wi-Fi Plugs, Model HS103.

The setup recommended the download of an app for my iPhone, so I found it and started downloading. The app was 445MB! I stopped the download, and laughed thinking an app that large needed to sit on my iPhone storage to simply turn an outlet on and off. I looked for another path.

As it turns out, there is a terminal-style interaction provided by Kasa for their customers. Not all product manufacturers offer these, but Kasa does. This also allows for the raw functionality I was looking for, which would provide fully custom home automations without the in-app promotions or the requirement to create yet another account.

We also have smart bulbs purchased years ago, and the Cree Lighting app sits on my phone all year round, just so I can make the lights flash a different color on Halloween or Christmas. Unfortunately, Cree doesn't offer the terminal-style interaction, and I'll be replacing the bulbs with Kasa soon.

The library is tplink-smarthome-api. I created a virtual environment, installed the library, and plugged in the first outlet into the wall. It automatically acts as a router for its own Wi-Fi network, which can be connected to via my laptop or phone. Once connected, I used the sendCommand to give the SSID and password for my home internet to the device. It responded with error 0, meaning success.

I then reconnected my MacBook to my home router, and with tplink-smarthome-api search, was able to find the newly issued IP for the smart plug. I used setAlias for the device as "Reading Light".

I could then turn the plug on and off directly from the terminal:

        
          tplink-smarthome-api setPowerState 10.0.0.28 false
          tplink-smarthome-api setPowerState 10.0.0.28 true
        
      

The reading light plugged into the smart outlet has a default "on" state when first plugged in. This means, after a power outage for instance, the light comes back on automatically when first receiving power. This was helpful in the automation, as it does not require a manual hardware interaction to turn on—it is "on" by default.

I created a simple shell script to turn the light on, wait 5 seconds, and turn the light off. I made the script executable with chmod +x and tested it in the terminal. It worked. I then looped the process with while true, and decreased the on/off time to a 2-second interval.

I then moved on to use the other outlets in creative ways. A small problem we have in the house when leaving in the morning is forgetting to turn off the kids' noise machines, which they have in their rooms to sleep. It plays music or white noise, paired with a small night light, and runs through the night. When we leave the house for the day and come back in the evening, I find myself manually turning these off almost every day. That time adds up quickly (when multiplied by 7 years of parenthood, and 4 years of two sound machines in different rooms, every day....).

The solution was to automate the outlet to turn off every day at 7 a.m., to turn back on after a five-second sleep time. By default, the devices are off when plugged back in, so it in effect turns off the night light and the noise machine via automation, every morning, saving me 15 seconds, every day, into eternity! That's an hour and a half per year, which I obviously need to write more technical learning blog posts that no one reads.

The next step was to automate the reading light in a more dynamic way. To do this, I used sunwait to find the sunset time according to my latitude and longitude. The script adds a 30-minute offset from sunset, to turn the light on during the waning sunlight of the day. A second script turns off the light. Both scripts were scheduled with the crontab. The first triggers at 3 p.m., well before sunset in both the winter and the summer; the second triggers at 10 p.m., as a sign to wind down in the evening.

By not specifying the time in the script, the crontab can be easily changed according to changes in schedule. If we want to start winding down earlier, I can make the reading light turn off at 8:30 or 9 p.m. If we want the kids to sleep without a noise machine, once they fall asleep, I can turn off the outlets to trigger a device stop at 11 p.m. or midnight, rather than having them sleep through the night with constant noise. It's a flexible and easily accessible way to tinker with home automations.

My introduction to IoT has me thinking about all other potential uses and home automations. However, I'm set on using the terminal-style interactions, which allow for /bin/bash commands and crontab automations. This to me seems the best way to learn about what's actually going on underneath the aesthetic but sales-oriented UI/UX of most modern products.