[slig]

Look up the ESP8266. It's a very cheap piece of hardware that you can program using the Arduino IDE. It can connect to your local WiFi easily and send a push notification to your phone.

So you can build something like this using a simple PIR sensor + ESP8266.

[gpribeiro]

Just made an account to say this and you beat me to it.

I built a garage door opening sensor using an ESP8266 (connected to my home wifi) and a magnetic contact switch. I'm also using TelAPI to send me SMS messages every time the garage door is opened.

It is very simple to do, and kind of cheap.

[andrey_utkin]

Could you please share any existing sources (schema, firmware)? Thanks in advance.

[impostervt]

Thanks, sounds similar to the particle photon + pir sensor I used for my version 1. It works, but i'm wondering if the phone part is overkill if I want to make this into a real product. Requires programming, an app on the app store, etc. If i have a second piece of hardware to receive and make noise, maybe that would be easier.