OpenEnergyMonitor Community

'Brand New' Emontx V3.2


I’m embarrassed to admit I’ve discovered a new, unopened emonTx V3.2 in my storage - complete with enclosure, battery holder and CTs but without the now-hard-to-find RFu board. While it must be 7+ years old, seems a shame to bin it and wondering how best to use it. I’d appreciate some inspiration if anyone has any ideas?

Ideally, I’d like to modify it to work with an esp822 and 2-3 DS18B20 probes to monitor a heat pump system in conjunction with my new emonPi and emonTH’s - but I’m guessing my options are now limited given there’s no microcontroller on this thing?

Is this more trouble than it’s worth at this stage?! Maybe one for my OEM museum now :slight_smile:

Many thanks

I’m not the expert @Robert.Wall is really, but is it the Microcontroller that is missing or the RFM chip?

If it is just missing the RFM chip, then it’ll work fine using the serial output in one way or another. personally I am a fan of using a Pi Zero rather than the ESP module but YMMV

The RFµ board is the middle layer of three, carrying an Atmel 328P processor. There’s no processor on the main board, only pads for the RFµ 328. It’s the RFµ 328 that carries the RFM12B/RFM69CW module.

So - all the emonTx 3.2 without the RFµ is, is the power supply from the a.c. adapter, the analogue signal conditioning and the I/O connectors (and even the a.c. input socket was the wrong size on some - The Shop had to send out an adapter).

Without a processor, you won’t even get that far - there’s no digital output of any sort.

@thedawnbefore’s only hope is to find (or make?) an RFµ 328 module. Mine is labelled “IoT Research”. I’ve got images of the circuit diagram and p.c.b, but not the Eagle files themselves. So “make one” would mean re-creating both from the pictures. Possible, but certainly not easy.

I doubt The Shop still has one, but it just might be worth an email.

(I’ve tagged the 1st post “Wanted” - in case somebody is looking there.)

1 Like

Thanks very much, both.

Given that I think I’ll divert my energy to implementing something more up-to-date and in line with the other new OEM kit. Thanks for the steer on RPi Zero @borpin

I’ll admit to a few mins of head-scratching at first, looking at an empty board wondering where the heck the processor was!

1 Like