emonTx Arduino Shield SMT and ESP8266 WiFi Adapter for EmonTx

I need to know, is it possible emonTx Arduino Shield SMT to work with ESP8266 WiFi Adapter for EmonTx.
Thank you in advance!

The emonTx Shield only adds the voltage and current inputs and the RFM69CW radio module to a standard Arduino. It has no serial data output of its own.

I think you should be able to connect an ESP to the Arduino, but beware the different voltages - the ESP will be damaged if you connect a 5 V digital output to it. Therefore, you must provide the 5 V supply via the ESP’s on-board regulator, and you must add voltage dividers to reduce the input voltage of the serial data into the ESP (see the circuit diagram of the emonTx Shield for details of the resistors you need).

Thank you for your reply.
The difference voltage levels is not a problem. There is a many ways to do it.
I saw in the Firmware Examples that there is the settings for choose how to send the data:
#define RFM69CW // The type of Radio Module, can be RFM69CW or RFM12B, or SERIALOUT if a wired serial connection is used.”
I would like to know if I set this on “SERIALOUT” and connect the ESP module, is it will sent the data to ESP.

Yes, that should be the correct setting. But check that the data format is correct for whatever is receiving the data. If necessary, you will need to edit those lines in the sketch.

If I’m right the ESP should be connected to UART. Is it correct?


Thank you very much! I will make the order, as soon as possible.

This is not needed. The ESP unit that we use for EmonESP (Adafruit Huzzah) is fully 5V tolerant on Vcc and serial pins. It can be connected directly to 5v no problem.

@glyn.hudson We didn’t actually know that @Miroslav_Sotiroff would be ordering from us, he might well have been ordering one that is not 5 V compliant. If you’ve seen his order, then the warning wasn’t necessary. Otherwise, it might well have been, because the one I looked at was definitely not rated for 5 V inputs.

Very true. That is why we recommend the Huzzah module: emonTx WiFi Adapter - Shop | OpenEnergyMonitor

OP pointed to firmware for emonTX instead of EmonTX Arduino Shield. Any reason we shouldn’t be using the firmware for shield? And wouldn’t it be Shield_CT1234_SerialOnly?


Where? Can you show us? The link in post no.3 is to a sketch that is configured by the user for any current (and many obsolete) devices.

As you don’t generally (if at all) have 3-phase electricity for domestic supplies in the USA, then the sketch you mention is probably better for you. But you must not assume the rest of the world has the same supply arrangements as you have, because they don’t.

I meant sketch, thanks for clarifying. I will use the single phase sketch. Thanks for quick response.