Difference between revisions of "EmonTH"
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Revision as of 21:56, 25 November 2013
Temperature and Humdity sensing options - Using DHT22 temperature and humidity sensor, or if humidity is not required just a DS18B20 temperature sensor.
Easy to set-up - the unit comes pre-assembled and pre-loaded with Arduino compatible firmware. If desired the code can easily be changed by using an USB to UART cable and the Arduino IDE to upload a sketch of your choice onto the on-board ATmega328 microprocessor.
Long Battery Life - The emonTH is powered by two AA batteries through a high efficiency DC-DC boost converter circuit, taking a reading once every 60s the emonTH batteries should last for 1-3 years. We recommend rechargeable alkaline batteries for best performance and environmental impact (see blog post).
Expansion Options - If desired the emonTH function can easily be expanded: remote DS18B20 temperature sensors can be screwed into the terminal block for outdoor temperature monitoring, multiple DS18B20 temperature sensors can be connected at once on a digital one-wire bus.
An optical sensor can be added for interfacing with a pulse-output utility meter or a relay board could be connected for controlling an appliance.
Flexiable choice of RF radio - Using the RFu328 with ATmega328 microprocessor as a common platform emonTH can work with either an RFM12B or Ciseco SRF RF radio
Microcontroller: ATmega328 on RFu328 board Sensors: DHT22 (temperature & Humidity) / DS18B20 (temperature) sensor options Power: 2 x AA from on-board holder, LTC3525 3.3V DC-DC boost converter to extend battery life RF Radio: Using the RFu328 with ATmega328 as a common platform emonTH can work with either RFM12B or Ciseco SRF radio Battery life: 1-3 years expected, see blog post
DHT 22 Temperature & Humidity Sensor
Power supply 3.3-6V DC Output signal digital signal via single-bus Sensing element Polymer capacitor Operating range humidity 0-100%RH; temperature -40~80Celsius Accuracy humidity +-2%RH(Max +-5%RH); temperature <+-0.5Celsius Resolution or sensitivity humidity 0.1%RH; temperature 0.1Celsius Repeatability humidity +-1%RH; temperature +-0.2Celsius Humidity hysteresis +-0.3%RH Long-term Stability +-0.5%RH/year Sensing period Average: 2s Independent sensor test report
See getting started with the emonth: Getting started with the EmonTH
power consumption, absolute max values