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emonTx TH

EmonTH remoteDS18B20.JPG


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

Port Map

EmonTH V1.4 PortMap.png



See getting started with the emonth: Getting started with the EmonTH



RF Connectivity



Electrical Characteristics

power consumption, absolute max values


EmonTH Github repository

Open-Hardware Design Files


Environmental & Life Cycle