Hacking a wireless weather display with an ATmega328P


Maker integrates his weather system into a Raspberry Pi-controlled sensor network.


The transmitter on embedded software designer Yveaux’s wireless weather station broke a couple of years ago, which left its indoor display out of commission. Not long after, the Dutchman received a new Alecto DKW-2012 system for his birthday. But it turns out that both weather stations lacked the ability to log data over an extended period of time. Channelling his inner DIY spirit, he decided to reverse engineer the transmitter’s protocol and build a sensor network system of his own.

weather-feature

The network is controlled by a Raspberry Pi, which collates the weather-related sensor data and stores it on his home server. The designer also hacked the broken weather station, including its pressure, humidity and temperature sensors, and proceeded to mount it alongside the DKW-2012. Admittedly, the setup looked “a bit silly” but functioned just fine.

Yveaux thought, “Wouldn’t it be nice to have a single weather station that logs all of its data and at the same time display this data on the wireless indoor display?” With some surfing of the Internet, he discovered that his weather station operated at the common frequency of 868MHz and was able to make the Pi speak its protocol.

“Some code found on the web details the protocol but I couldn’t find any project that transmits weather data. I did, however, find some code by SevenWatt that uses an Arduino and RFM69W to transmit OOK modulated signals.”

WS2900

Using this code as a base, he added a Moteino (ATmega328P) and an nRF2401+ transceiver to send data to the Pi. A DVB-T USB stick is tasked with capturing and analyzing the time and weather information, which is relayed over to the indoor display for viewing.

“My home server, which stores the weather data in a database, also publishes this data to an MQTT broker. A Node-RED installation subscribes to this data and republishes each value to topics recognized by an MQTT MySensors Gateway, which I wrote some time ago. The gateway distributes these values to wireless sensor nodes in a MySensors network,” Yveaux writes.

The setup has been running for a few years and the database now contains over one million samples. Intrigued? Head over to the Maker’s project page here.

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