Smart meter online

After 3 weeks, finally the end result came dangerously close ­čśë

Every time I finish something new and the time comes to actually start using it, I get excited – will it work? Cause testing in the office is something completely different than seeing real live data coming in! (yep, I forgot to check if I still had a free connection on the switch in the fuse box…)

Simplecortex with Proto Shield

The Simplecortex had been running without any problems during the last 2 days so it was time for the last part: inverting the P1 signal before it arrives at the Simplecortex UART0. I had an old Arduino Proto Shield laying around and put an 7470 inverter on top.

The ‘receiving end’ i.e. my Domotica system is ready – which consisted of adding an MQTT client to it and making sure it subscribes to the necessary topics.┬áJust 2 more wires that needed to be soldered and I could hook up the Simplecortex to my smart meter… couldn’t wait!

And this evening I decided to remove the laptop that was logging the P1 data to a file from day 1 and replaced it with the contraption you see below.

Smart meter online!

And this is what it publishes (output from a MQTT subscriber):

/P1/powerusage1 00311.543
/P1/powerusage2 00158.107
/P1/powerdeliv1 00000.000
/P1/powerdeliv2 00000.000
/P1/tariff 0001
/P1/powerusagec 0001.88
/P1/powerdelivc 0000.00
/P1/gasusage 00027.758


The hardest┬ámost exciting part was developing the code in C for the Simplecortex. For my work but also at home I see a lot of code, in all kinds of languages and I can follow what the code should do – but getting started with writing my own code in a language which I hadn’t really used before took me some time – I just kept on changing things because I was not satisfied. Now I am (thanks, JC!), although there are still some minor things I have to work on. But those are not necessary for now; I can flash the Simplecortex later, when everything is completely finished software-wise.

Now I can start logging gas usage again and I can stop using my DIN rail mounted KWh-meter with S0 output which I used for power usage (but not before I’ve had a chance to compare it with the smart meter, though). Source code will be available on GitHub soon (account has already been made) .

Next project that will be handled in a similar way: the Opentherm Gateway! For that one the Simplecortex needs to be able to subscribe as well!

Edit: the P1_Publisher project has been committed to Github some moments ago:


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  1. Pingback: A smarter smart meter - Digits Domotica Blog

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