WiFi only EmonTX

I wonder if there is now a market for a WiFi only EmonTX? I understand why RFM was used originally, but life has moved on.

Just a thought :smile:.

They have the EmonESP wifi module.

I think the question was not “Is there a WiFi module?”, but “Is there a need for an emonTx with only WiFi and not the UHF RFM module?”.

One immediate answer is, a separate 5 V USB power supply is required to support the ESP module, whereas the RFM version can operate with just the a.c. adapter providing the power. (It’s because the RFM requires a lot less power than the ESP, so it doesn’t significantly disturb the output of the a.c. adapter, as it would if you drew the current required by the ESP from it.)

So it’s not just a straight swap of ESP and RFM.

Yes appreciate that, just in terms of how the devices are now being used, and with a proliferation of other means of collecting temperature (another reason for the low power RFM), an EmonTX with just the wifi rather than having to disable the RFM, it seems like something to be explored. Plus the ‘addon’ is horrible :frowning:.

Absolutely. However, I feel that the Arduino platform severely limits the capabilities of the emonTx (e.g. a 3-phase ‘Solar’ device - for which there is a demand - is impossible without an external ADC) and so future development effort should probably be directed instead towards reviving the STM32 development.

Don’t disagree with that, just wondered if a version of the EmonTX without the RFM chip and a slightly neater way of fitting an ESP board and supplied ready to go might be a relatively simple win. If I was looking, it would be my preferred route right now.

That’s what I thought you had in mind. The battery is all but useless with a WiFi adapter, so removing that should leave enough room inside the case, but there could well be problems with proximity of the antenna to the case.

But I still perceive a demand for a 3-phase capability that goes unfulfilled. A 3V6I STM32 with Wi-Fi – there’s an appealing thought.

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There is a provision for an ESP module on all emonTx PCBs, V3.4.3 and up. Beneath the battery holder, there is room for a header - clearly seen in this photo:


Unfortunately, there was a mistake made during manufacture resulting in the current batch having the holes full of solder. The next production run of the boards will not have this issue.

Ah interesting.

Could you do some boards without the RFM chip specifically for WiFi only?

Is there info anywhere on how to connect up if anyone was interested?

Why not offer a prebuilt WiFi version?

I don’t think there is. I do know that the RX and TX pins have been swapped around relative to the existing header - therefore connecting the ESP is a lot simpler.

This is very likely to happen.

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Great. A header and a wee daughter board for a WemosD1???

Plug and play.

Yes, we are planning on offer a WiFi version pre-built once we get a another batch of boards next month with the header clear of solder.

To start with we probably won’t remove the WiFi module, the module is only £1.50 in qty, therefore it would not be cost effective to do a specific manufacturing run without it. It’s something we could consider in the future. However, having the module in place could be useful since a emonTx with RFM + Wifi could be used to receive data from an emonTH then post to emoncms.

We have a guide on how to use the WiFi module running EmonESP with the emonTx: Using the emonTx v3 with the ESP8266 Huzzah WIFI module - Guide | OpenEnergyMonitor
The socket on the PCB is very easy, the Huzzah module will just plug straight in since the Rx and Tx have already been swapped over.

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OK great.

There was a bit on this thread from @Robert.Wall about needing the antenna connected even if not in use. I guess you’ve dealt with this issue but that was where my thought came from. I did wonder if it would be cost effective or not.