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Recently I’ve put together a simple e-paper (a.k.a. e-ink) display which shows current time and temperature. Why e-paper? Unlike LCD it provides better contrast at any angle and unlike TFT it doesn’t require backlight. The only downside is long screen refresh time (~4 s in my case).

The idea was to get current time from an NTP server and temperatures from Home Assistant instance which in turn gets them from wireless sensors.

I used to use web services such as OpenWeatherMap to monitor outside temperature in openHAB. I found out that sometimes they’re not very accurate and naturally they fail when the internet is down. So I decided to measure the temperature myself. After some searching, I decided to settle with battery powered ESP8266 wireless solution. The advantages are the following:

• no wires;
• low cost;
• easy programming via familiar Arduino IDE;
• long battery operation with deep sleep mode.

In this post I want to share some details about my simple low budget smart home system based on 433.92 MHz receiver/transmitter controlled by Arduino. It can be easily extended with many cheap wireless devices, such as door bells, remote sockets, smoke alarms, leak detectors, etc. I’ll describe how to control remote socket, receive alarms from wireless smoke detector and draw a plot of room temperature obtained from regular wired sensor.