Building a wireless environment sensor to run for over one year on a CR2032

Building a wireless environment sensor capable of running for almost 2 years on a single CR2032:

Intro This article will discuss and demonstrate how to build a remote Temperature and Humidity sensor based on a Whisper Node and a DHT11 (worst sensor ever, I know)., capable of running for well over a year on a single CR2032 coin-cell.

The remote node will be configured to transmit data every 60 seconds to another Whisper Node, acting as a gateway/base station and located 100 meters away. The data will be finally uploaded to a Google Could server running InfluxDB and Grafana to display the data.

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Lots of detail on power and configuration. But little RF detail:

? What is the modulation mode
? What is the expected range?
? What is the receiver sensitivity
? What signal processing is done, with what effect on needed SNR?

Is this LoRa or other? What communication / standard? Interoperability with anything else?

Just so much activity in this area, hard to follow it all…

Hey Terry,

Yes I agree there are lots of RF options at the moment. Well the Whisper Node has RFM69W built-in ( It's a subGhz digital module based on the Semtech SX1231.

This is not LoRa. Here the main features:

Modulations: OOK, FSK and GFSK TX Power: 13dBm (20dBm for the High power version) RX Sensitivity: -120dBm at lower bit-rates The Power consumption for TX varies according to the TX power, I've documented it here: The TX mode consumes around 16mA.

I'm currently using the RadioHead Driver:

For the application protocol you can basically use anything, but I normally use with very short binary messages to preserve energy. Here an example how I pack the messages:, which is basically a "clone" of a CAN Bus frame "b", headers + 8 bytes of payload.

In terms of Interoperability, you can talk with any other device using RFM69 or Semtech SX1231.

Hope I clarified most of your question. Soon I'll be including the AVR and Python code, as well the steps to install and built the Grafana dashboard.

Update: regarding the range, as all wireless related it varies. The project in the original post is designed to handle 100m at higher speeds, but here some tests I did at lower bit-rages (19200bps): |500x295