AVR-DB: emonTx V4, new hardware in progress



I want one


I’m Spartacus, and I want one too,… :slightly_smiling_face: :rofl:


No, I’m Spartacus!

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Thanks all!

A couple more pictures of the new boards, we received the first 50 out of 500 today, here are just a few:

A fair bit of final box build assembly to do over the next few days alongside getting the shop entry online in the shop.

Here’s an installation example, this one is at my house, a small bit of trunking is magic for hiding away the CT wires! :slight_smile:

I have the EmonTx4 transmitting to a raspberry pi with our new SPI RFM69 radio receiver board in the livingroom attached to a Elecrow 7" IPS display. Il post up more about that soon.


Here’s another example installation with emonTxV4 and 6x CT sensors in my house:

I’ve actually got the emonTx V4 hardwired via USB-C to the emonBase (hence no antenna) and the emonBase is powered by the emonVS which in turn is hardwired to 240V via a 6A RCBO which makes for a tidy installation without any power adaptors.

Most of the CTs are installed inside the fuse box / consumer unit and run down to the emonTx V4 via some flexi conduit and trunking


You guys are living the dream… I think I will have to invest when they are up on the shop.

What’s the plan with the expansion board? I assume its a way out yet and next year?

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Thanks @whitecitadel

Yes expansion board is some way off. We’ve been focused on just getting the core single phase + 6 CT input configuration sorted for now. The next step is 3 phase firmware support and then later expanding to 12 CT’s.

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Thanks, and understandable.

6 Circuits would get me started with finally monitoring divert to the hot tank properly (no mains in airing cupboard, so not ideal with EmonTX on battery) plus the main house rings and perhaps the cooker as the heavy lifting load.

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These look brilliant - great word lads!

I haven’t been keeping up-to-date but I see there are plans for an ESP32 adaptor board, presumably to give WiFi connectivity? Are there any plans for an ethernet version of the EmonTX V4?

I am a big fan of ethernet, particularly for mission critical pieces of kit like my EmonTX (Arduino shield on an Etherten controller).

Not that I am aware of. You can always connect something like a Pi or Pi Clone to the serial output. Because of the form factor, there is currently not enough room to do this as an internal add-on. At some point the RFM could be replaced with an Ethernet port (in terms of space).

There is an esp board (WT32-eth01) with builtin ethernet which should be possible to easily use with the ESPHome component.

Yep, something like the WT32-ETH01 is exactly what I was thinking about. I can’t wait till these are available - I currently have 4x of the EmonTX arduino shields (1x in my current house running perfectly, and 3x waiting for my new build) but this v4 might make life a bit easier.

In terms of easier, using ESPHome, it would be straight forward to get it up and running. You might be able to squeeze it inside :slight_smile:

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Thanks Brian, so assuming the new EmonTx v4 hardware is available to buy (hopefully not far away), what else do I need to get it running with a WT32-ETH01?

I can’t find too many details about the new v4 hardware, other than it supports 6 CT clamps. How would the ESP32 module link up to the EmonTX hardware?

I presume I would still need the EmonVs unit for accurate voltage sensing?

Just connects to 3.3V, gnd, TX, RX. I built a small add-on board to connect to the headers available (Trystan posted photos of his factory addon boards). To get it inside the case you’ll need a bit of case modification for the cable.

My ESPHome component is still in development, but it works :slight_smile: I’m just working out how best to enable folk to use it is they do not use HomeAssistant.

Yes and it will power the device as well.

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I will keep an eye on the store and hopefully will be able to get my hands on one soon.

Thanks Brian, very helpful feedback.

There’s an ethernet equipped Pi Pico (W5500-EVB-Pico) but I don’t know if it’s compatible with the proposed Pico interface board or if it would fit in the enclosure.

That is quite neat (W5500-EVB-Pico - Pimoroni) but there is insufficient height to fit inside the enclosure as things stand. It would need an add-on board such that the Ethernet board could be fitted upside down.

If someone had the wherewithal to create a 3D Printed enclosure for the TX4, it would make this feasible.


Hello all, we are happy to say that the EmonTx4 is now available in the shop :tada: we will be able to ship the first set of orders early next week.

We are starting with a quiet launch as we continue to gear up with this new product. For those of you who have been following along here for a while, we would like to say thank you with a 10% early bird discount code O3N5S93TFQ (Available until next Monday 28th of November).

Items in progress

  • We are in the process of moving from the old guide documentation to a new site based on ‘Read the docs’. Please see: https://docs.openenergymonitor.org/emontx4/overview.html
    This will house both the existing documentation e.g emonPi and emonTx v3 in addition to the new hardware. This new implementation builds directly from the documentation placed in e.g the emonTx4 GitHub repository itself, so you can choose to either view the same documentation on github or with the nice ‘Read the docs’ theme.

  • There’s more to add to the EmonTx4 documentation section as well, including using the EmonTx4 with an integrated WiFi extension board, a heat pump monitoring focused install guide discussing how to use the broken out analog input to interface with a voltage output Sika flow meter. Details on the temperature sensing and RFM69 radio among other items.

  • New emonSD image release, we will do a separate announcement about this over the next few days.

  • EmonTx4 Pi Pico, Pi Zero, ESP8266 and ESP32 extension boards will be available as bare PCB development boards in the shop (Shop items still to be created) - these are only for those happy with a bit of soldering and code uploading for the time being.

  • We also need to create the shop item for the lower cost emonVs mini (voltage sensor only - no integrated power supply) and the ACAC adapter converter board.

  • This first release is the single-phase 6 channel configuration, the 3-phase version will follow later. If you do want to order an emonVs voltage sensor with the hardware capability for 3-phase so that it can be used when the 3-phase firmware is available, please email us and we can arrange that: [email protected].

We would welcome suggestions or pull requests for changes to the documentation. The emonTx4 documentation files can be found on github here: emontx4/docs at main · openenergymonitor/emontx4 · GitHub

Let us know if you have any questions regarding the bundle options selection.

@glyn.hudson has also just updated the theme on the shop to something a little more modern :slight_smile:

Thanks everyone!


@TrystanLea - That’s fantastic news! Well done you guys.

Am I right in thinking that we can add Wi-Fi at this stage but it requires soldering on the module?