| Right now I have the following on a breadboard (see [1] for the illustrated version) * ATTiny84 * DHT22 temp/humidity sensor * 433 MHz TX module * 3 x AAA batteries * LED used for signalling (like booting up) Initially I was using an Arduino Nano, but I couldn't optimize it enough so that it can live only on batteries, so I went with the ATTiny which is pretty impressive. My oldest sensor node has been running for over 6 months on the same batteries and it still has some juice left (3.9V currently, it should work until it gets below 3.7V) After I've settled with a final design I'm planning to solder it on a perfboard. The DHT22 sensor accuracy is my only issue left, specifically the humidity measurement part (see [2] for some extensive research by someone smarter than me). Everything is on github[3] but it's pretty messy at the moment (hardcoded and such) because there's never enough time for everything. [1] - https://raw.githubusercontent.com/ambient-monitoring/node/ma... [2] - http://www.kandrsmith.org/RJS/Misc/Hygrometers/calib_dht22.h... [3] - https://github.com/ambient-monitoring |
