Can you use emonTx V2.2 With the ESP8266 Huzzah WIFI Module


I need to add monitoring to a Battery system. It is AC to DC (Lux AC + Pylontech batteries) so I will fit a CT on the mains input.

I have lying around an old emonTx V2.2 and a spare Huzzah WIFI Module. Could I use this? The documents only mention emonTx V3

I don’t see why not. It’s got the same processor with the same capabilities. You will need to modify the output format of whichever sketch you use - you can lift that pretty much intact from one of the V3.4 sketches. You’ll also need to check the serial baud rate that the ESP expects, and change your sketch to suit.

You could even run emonLibCM on the V2 if you wished - a lot of the work I did on that was done on a V2 because of the availability of outputs that I could hang a 'scope on to check the timing, etc.

The recent problems surrounding the ESP8266 stem from it sending back unwanted data to the V2. As long as the V2 doesn’t look at the serial port and try to act on incoming characters, that won’t be a problem (or you can leave the incoming data connection off).

Many thanks.
I will give it a go. The only slight issue might be sourcing the CT pcb socket as this board was only built to monitor temperature. If they are the same as the sheild I may be able to take an unused one of the sheild I have and use that.

They’re not. According to the parts list I have, they are “20-0144 3.5mm pcb jack (Rapid Electronics)”

And that looks like the one.

Is it possible he has an emonTH?

The emonTx V2 was supplied in kit form for assembly by the user, so it’s perfectly feasible to build it with only the temperature sensor input - also using the same 3.5 mm jack. The V2 predates the emonTH by a fair while, so while by no means conclusive evidence, the only way to measure temperature in its day was to have the V2.

The parts list file I quoted is dated February, 2012, The V2.2 schematic is dated 28/8/2013. The earliest emonTH sketch I have is dated November, 2013.

Ian’s been around here for a long time, I think he’s going to be right about what he has.

D’Oh! How could I forget that. I built one in 2013. :thinking:
'cept I used all of the parts. :wink:
Damn! where does the time go?

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Same here.
And I’ve no intention of parting with it - having most if not all the I/O easily accessible makes it exceedingly useful. I only wish the radio wasn’t soldered down quite so effectively, else I could put a RFM69CW on it. Now that would be very useful too.

A heat gun with an appropriately sized “nozzle” works well to desolder comonents with a
footprint the size of the radio module.

I thought of that, and I do have one, but protecting all the other parts is the worry. If I’d got a huge soldering iron, I’d fashion a “U” shaped bit with the correct dimensions to get on all 14 joints at the same time. :smile:

Hence the need for a nozzle that’s (roughly) the same size as the footprint.
If the gun produces sufficient heat, the solder will melt and the module can be removed before
other components are damaged. IIRC, the temp specs of most components are rated at max
heat for 10 seconds. It should be fairly easy to get the board unsoldered in half that time or thereabouts.

Yes, but that’s the lead temperature, not the body. There’s an electrolytic capacitor less than 1 mm away from the module, and I wouldn’t fancy its chances even with 5 s of enough temperature to melt solder.

If that cap is a through-hole devce, it could be removed prior to the “surgery.”
The key is the nozzle, and the distance the nozzle is held from the board, which is quite close.

When I worked at a USN repair depot, we had a hot-air solder/de-solder station for a few months.
(it was a demo, but they wound up not buying it as the price was quite steep) At any rate,
it worked well and didn’t fry anything else on the boards we used it on. But, as I mentioned, the
heat it produced enabled the job to be done quickly.

The whole V2 is through-hole, except for the RFM12B - and the processor is socketed.

I looked up my old orders. I purchased a number of
EmonTX Low Power Temperature Node kits in 2012. From memory only the parts needed for temperature measurement were supplied. The kit cost £18.50 and I got a video of Glyn or Trystan cycling to the post office as proof of posting!


I’d forgotten the kit, but remember the video. I think it was Trystan. It was downhill, feet off the pedals, all the way. I don’t think we got to see the slow grind back up the hill afterwards. :hot_face:

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I have checked the emontx and the Huzzah and they both function.
@Robert.Wall you mentioned I could use probably use emonLibCM. Is there a sketch you would suggest as the best to start with?

Look at the example sketches that come with emonLibCM. The only real differences between the V3.4 and the V2 is the pin numbers and the radio settings.

Here’s my “crib sheet” giving all the relevant I/O.
emonTx (1.1 KB)
and, for what it’s worth, I’ve found my test sketch:
EmonTxV2CM_868.ino (5.9 KB)
That one is by no means a “production” sketch, the ‘payload’ to emonCMS is totally non-standard, it was adapted from the V3.4 sketches simply to prove that the library would work with the V2.

Many thanks.

They are going to be very helpful.