A smart home with a pet cat: how to automate your daily routine at home

Can you automate your home so that the kitty litter box sends messages to WhatsApp letting you know it needs to get cleaned, and the TV displays a message when the bathroom is free? Our community manager

Devices for Apple HomeKit may include an Apple TV set-top box, a temperature control sensor, a door or window opening sensor, a smart lamp, a smart outlet, and a smart LED strip

So my existing Apple TV set-top box served as the starting point for my research.

Right off the bat, I'll note one unpleasant feature of the commercial systems out there: only compatible, pre-approved devices can be used with them. This is true for Apple, Xiaomi, Tuya, Aqara, and so on.

Right from the start, I opted for an unconventional approach – instead of installing light bulbs and smart sockets all over the house, I decided to start with climate control. I found a HomeKit-compatible air purifier online, installed and set it up. It was easy, everything worked right out of the box. It was even a bit boring. 🙂

Right after that, I wrote a review article on Sprut.AI, a popular portal at the time.

My Raspberry Pi

It was easy to deploy Homebridge on my new SBC, after which I was finally able to connect my homemade CO2 sensor to the system. Now, if the room gets stuffy, the air purifier automatically starts, and I know it’s time to open a window. I later realized that the air purifier itself has no effect on the CO2 level so I addressed this. I’ll explain what I mean, so that you do not repeat my mistake without realizing it.

The air cleaner cleans the air from dust and odors, but it cannot get rid of CO2. Right now, my system runs on forced air supply. There is a hole drilled in the wall of the house that opens to the street. It has a fan with a filter that blows air in from outside, cleans it, and delivers it to the room. The CO2 sensor works in conjunction with this supply system. If the carbon dioxide level is above 1200 ppm, you could get headaches and fatigue. I have set up the system so that when the concentration is above 1000 ppm, the air supply is automatically turned on, and when it drops to an acceptable level, it is turned off.

Given the opportunity to connect any third-party device to the smart home, I started buying various sensors from Aqara, Xiaomi, and Tuya and integrated them into Apple HomeKit. Plus, I built a few more ESP-powered homemade devices. However, they have a significant disadvantage for my use case: they only work over wifi with specialized energy-efficient protocols for a smart home. I really like Zigbee: it only takes one battery to power a sensor, and it will last for years without needing to be replaced. Plus, wifi devices need external power (I know, CO2 sensors, even Zigbee ones, are not battery-powered, but I’m talking about other devices). Moreover, the devices cannot be used for signal relaying, unlike Zigbee, where each device can act as a router for any of its neighbors that are not in direct contact with the hub. However, we have to live with the fact that a smart home incorporates gadgets on wifi, Zigbee, and even Bluetooth.

Everything is evolving, and soon, this menagerie of protocols will be replaced by a single convenient protocol – Matter. There are already devices that support it on the market. They say that it will make everything easy and simple. We’ll see.

Taking Home Assistant to the next level

After a while, Apple's system became claustrophobic for me. I wanted to create more complex automation options than the ones provided by the vendor. For example, I wanted the lights to come on in specific places when certain conditions were met, or to start chains of actions when certain complex conditions or threshold values on the sensors were reached. Simply put, a smart home is defined by the automation of routine processes. Everything is configured so that in routine scenarios, certain actions are performed without human involvement. Without a certain level of complexity (by HomeKit standards) scenarios this isn’t possible.

This was the impetus for my decision to expand my smart home system beyond Apple HomeKit to incorporate an advanced sensor system that can serve as an automation engine and a hub for other devices. I chose Home Assistant, although I also tried Node-RED, which is popular in some circles. Home Assistant’s huge community and wealth of publications online helped it win out. So I decided to deploy Home Assistant on my Raspberry Pi, meaning that I wouldn't need Homebridge anymore.

At that time, if you installed Home Assistant, you had to be prepared to spend a lot of time on the command line. This didn't scare me, rather, I turned it into my new hobby, as I had never had any problems with Linux thanks to my professional background. Despite the rigorous demands of Home Assistant (especially its early versions) on the user, it offered expansive possibilities, allowing me to fine-tune all my devices and the interconnections between them. The large Russian-speaking community on Telegram was very helpful, and there is quite a lot of information on YouTube. My capabilities grew, and along with them, my smart home began to develop in new, dynamic ways.

Apple TV went from being my main controlling device to being a humble multimedia component of the system. Since one of Home Assistant's functions is to serve as a bridge with Apple HomeKit, anything connected to Home Assistant can be added to HomeKit as well. So I can still control my smart home and all connected devices through the Home app on my iPhone, or, say, ask Siri to raise the curtains in my hall.

At first, I deployed a system based on Raspberry Pi, but the Raspberry Pi has certain drawbacks – an unreliable disk subsystem based on an SD-card and a noisy cooling fan which kept my wife awake from the next room. 🙂 So I found a ready-made Gigabyte mini-PC with a silent passive cooling system and an SSD drive.

Smart curtain, air inlet and Zigbee sensor for ficus

Sensor for the kitty litter box. There is a vibration sensor on the kitty litter box so when the cat visits it, the extractor fan in the bathroom automatically turns on. Then we all receive an urgent notification on Telegram to perform a hygienic procedure on the litter.