I made a new friend, and her name was Sandy. I say ‘was’ because I just learned that my neighbor’s toddler calls her Sassy, so I think I’m obligated to say that must be her real name and I just misunderstood the pronunciation.

There are at least three other families that put food out for Sassy and her two kittens, but I’m pretty sure I’m the only one she stays with for extended periods of time. She isn’t vocal when she stops by though, so instead of opening the door every 10 minutes making “pssspspspsp” sounds at my neighbors who are just trying to enjoy a walk at night (actually happened), I decided to make something that could notify me when she might be looking for some wet food or the warm bed of my folded towels.

To detect her or other friends, I strategically located the outdoor food dish in a way that would put the unsuspecting felines in the line of sight of a proximity sensor.

The proximity sensor consisted of a Sharp infrared sensor and Particle Photon microcontroller. The Photon is an easily interfaceable Arduino with a built in ESP8266 Wi-Fi module. On top of that, the Particle environment uses cloud-based event handling making it perfect for sending confirmed cat sighting messages to my phone.

I measured the distance from a post on my porch to my house and used that as the baseline. Any obstructions result in a measurement less than the baseline, which is a moving average minus a margin, results in a confirmed sighting. This confirmed sighting created an event that was sent via Wi-Fi to the cloud. And then the tricky bit – how to go from cloud to phone for free? I ended up using an app on my phone called IFTTT, If This Then That. It’s able to handle events published on the Particle Cloud and then shoot me a notification when the status changes.

That’s it! No more ‘ships in the night’ scenarios hopefully 🙂