1. Xose Pérez
  2. emoteino



Moteino Energy Monitor

A simple energy monitor shield for Moteino and the needed firmware to make it work with different configurations.


  • LiPo battery connector with battery monitor at A7 (470k resistors for low power)
  • Simple biased reading (low consumption voltage divider) with optional burden resistor
  • 3.5mm jack input compatible with most CT out there
  • Stackable up to 3 shields to read 3 different lines.
  • Jumper pads to select input pin (A1, A2 or A3)

Check my Moteino Energy Monitor Shield post for further information about this project.


The hardware is shield for Moteino with a battery monitor circuitry and a 3.5mm plug for commonly available current transformers (a.k.a. non-invasive current sensors). There is a footprint for an optional burden resistor (SMD0805) and a bias voltage divider using 2 470K resistors for low power consumption.

Energy Monitor Shield Schematic

The battery monitoring is based on a voltage divider with (again) two 470k resistors. The downstream resistor is tied to GND and the mid point to A7.

Energy Monitor Shield

Firmware for Moteino + RFM69


The code is very straight forward and there are comments where I thought it was important. It uses the following libraries:

These libraries will be automatically installed if you use PlatformIO.

It also relies on my RFM69Manager library to wrap RFM69_ATC. This library manages radio setup and also message sending protocol. Messages from this node have the following format: <key>:<value>:<packetID>. Packet ID is then used in the gateway to detect duplicates or missing packets from a node. If you don't want to send the packetID change the SEND_PACKET_ID value in RFM69Manager.h to 0.


Rename or copy the settings.h.sample file to settings.h and change its values to fit your needs. Check the descriptions for each value.


The project is ready to be build using PlatformIO. Please refer to their web page for instructions on how to install the builder. Once installed connect the Moteino to your favourite FTDI-like programmer and:

> platformio run --target upload