OpenEnergyMonitor Community

Pulse Logging of Several Sub Meters

Hi All
Can anybody recommend hardware that will monitor several water meters (three off) to pass into a EmonPi. The reason for all of the meters is to monitor general hot water and shower cold & hot.
I have a EmonTx nearby but that will only log one meter.


@pb66 says you can feed the pulse inputs directly into the GPIO of the RPi inside the emonPi - but there’s a practical problem in that you need to get the wires inside the case.

And @dBC recently pointed out that any digital input of the Atmel328P can be used as a pulse input. But again, there’s the problem that spare unused digital inputs aren’t brought out to pins on the emonTx.

Hi Dave, I implemented that with an Arduino pro mini and an RFM69, check out this project:


Thanks @franck102
I’ve ordered a Arduino board and a RFM69, will let you know how I get on.


Sound good.

If that is your first project with an RFM69, do remember to keep it away from 5V - in particular if you program the pro mini with a 5V serial adapter you’ll want to disconnect the radio first.
I use coiled spring antennas which gives a good range/footprint compromise; and straight 1/4 wave dipoles when I need more range.


That would actually be a 1/4 wave monopole. :wink:

If you use a groundplane with it, then effectively it’s a dipole, but is still referred to as a monopole. :grin:

Really? I have a straight wire going up from ANT, and another identical one going down from GND… doesn’t that make it a dipole?


There was a long discussion on improving signal here Improving RF signal strength emonTH emonTX

Indeed it does.

If each of your elements is 1/4 wave long, (if not, they should be) then it’s a 1/2 wave dipole.
(you referred to it as a 1/4 wave dipole)

The measurement referring to the antenna wavelength is made from end to end of both
elements vice just one of them.

Ah ok, I got the length wrong in my description, the total length is indeed 1/2 wave length:) I learned that from the Arduino forum, and from my empirical trials it has worked much better than ground planes.

With the LowPowerLab library which has transmit power control I can cross the house through two stories at level 4 out of 32, and I’ve had a couple low power setups running for over a year on 2 AA batteries.


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Build a 12 input pulse counter - multiple input pulse counting
Arduino Pulse counter sketch by Trystan, and tested by Glyn.
Use a serial connection to to your EmonPI