reading smart meter P1-port with esp8266

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Hi there,

A couple of weeks I found out that jantenhove did a great job by sharing his sketch for reading his smart meter values to Domoticz. It can be found here: https://github.com/jantenhove/P1-Meter-ESP8266

I tried to use it and it works like a charm. However, I’m not using Domoticz for my daily setup, but I am using pimatic for that.

I tried modifying his sketch to post the values to the pimatic API, but with no succes.
Can someone help me to rewrite the HTTP GET/POST requests so I can use it for pimatic?

@lxz When I needed to adjust the Arduino sketch for pimatic, I used as an example from @incmve https://github.com/incmve/ESP-pimatic.
He has a P1-Meter-ESP2866 cloned Maybe he will know more.

Thanks! I think it will help indeed, will give it a try

there’s a plugin for the p1 smart meter.
https://github.com/saberone/pimatic-smartmeter

guess your pimatic system is not located nearby your p1 meter?

No, not even close. Thats why i’m looking for a wireless solution

Thanks for mentioning the plugin though. Maybe I can use a second rpi for that

I think @koffienl can help you. He has done a amazing work with his ESPimatic!

Normally it should be easy to push data into variables in pimatic.

Shouldn’t be very difficult, I gues … but I don’t have a smartmeter to test
Perhaps in a future version

@koffienl i think you need only to provide a simple Pimatic bridge. The P1 code is ready as @lxz mentioned

I’ll ask @incmve when I see him

I have the git forked but not done anything with it yet, my pi is next to my meter
@lxz do you have your code somewhere so I can test?

@incmve The modifications I did on the code didn’t work, so I don’t have much to share I’m afraid.

What I tried was modifying this line:
sprintf(url, "http://%s:%d/json.htm?type=command&param=udevice&idx=%d&nvalue=%d&svalue=%s", domoticzIP, domoticzPort, idx, nValue, sValue);

to somthing like sprintf(url, "http://%s:%d/api/variables/%d/%d/%s", domoticzIP, domoticzPort, idx, nValue, sValue); and then I got stuck because that is not the way the pimatic API works. You see, I’m a complete noob in programming

@lxz said:

You see, I’m a complete noob in programming

Me too when I have time I will give it a try

I’ll try to have a look at this tonight, it shouldn’t be too hard to adapt this for pimatic.
I’m already using an ESP to read my P1 port and send it to pimatic via MQTT (and to Thingspeak via http), so it can definitely be done (and it works like a charm!)
This is what I am using now, it’s just a bunch of code hacked together (I guess from one of koffienl’s early examples).
https://github.com/renearts/ESP8266-P1-transmitter

I always wanted to clean it up and use a direct pimatic API call and add OTA updates, this project looks like a very neat start for this.

To get you started quickly:
Have a look at my other repository/sample project (also an early koffie’s esp-pimatic):
https://github.com/renearts/esp8266-pimatic-Arduino/blob/master/esp8266/esp8266.ino
Starting at line 197 you can see how to send a variable to pimatic via the API (temperature and humidity in this case).

Ultimately it would be awesome to have the P1 port readout integrated in Koffie’s esp-pimatic project, though a nice step in between would be to have such a nice interface as well

edit:
Ok, can’t help it but already started a bit with adding a SendToPimatic() function: https://github.com/renearts/P1-Meter-ESP8266

Does anyone know if/how it is possible to update multiple values in one API call?

Ok, did some quick hacking, the better copy/paste kind of stuff and updated my previous project:

https://github.com/renearts/ESP8266-P1-transmitter

Kind of works already, though need change the number format, it currently rounds to whole numbers (kW) so actual usage remains mostly zero --> think I might fix this tomorrow.

I hope/think I just fixed the last problem; had to change the internal variables which store the readings from long to float. As I am at work I cannot test it yet, but I will tonight.
Just a quick note: I am using the hardware serial input instead of the SoftSerial stuff which jantenhove uses. It’s not hard to put the SoftSerial back if someone likes that better. I guess it does not make big difference though, but I like using hardware peripherals when they are available. Only advantage of the SoftSerial is that I would be able to ditch the inverting FET.

Thanks a lot! I will try it when I get home. By using hardware peripherals you mean I have to use the schematic with BS170?
(If so, I have to get one first)

In that case, yes. But I might have good news for you! See my latest commit: just uncomment lines 68/69 and 517, comment/delete line 516 to use SoftSerial again (currently on pin D5)

Nice work but a quick try is giving some errors

'hour' was not declared in this scope

havent had time to dig trough the code yet

Yes that’s possible as Time.h was not yet included, seems to be needed for the interface.
Just pushed a new version; just tested it and it seems to work.
I did encounter some problems when trying to compile with the SoftwareSerial though, but haven’t got time to sort that out now.

Still facing a little problem with the float -> string conversion. In pimatic I’m using a VariablesDevice, I was using number as type, but then I get errors that pimatic is receiving a string (which in fact, it is). So I’ll need to figure out to either convert the string to a number, or to send/update the variable as number. Maybe someone has a good suggestion?

      "id": "P1_meter_readings",
      "name": "P1 meterstanden",
      "class": "VariablesDevice",
      "variables": [
        {
          "name": "mEVLT",
          "expression": "$mEVLT",
          "type": "string",
          "unit": "kWh",
          "discrete": true,
          "acronym": "Electricity Consumption Low Tariff"
        },
        {
          "name": "mEVHT",
          "expression": "$mEVHT",
          "type": "string",
          "unit": "kWh",
          "discrete": true,
          "acronym": "Electricity Consumption High Tariff"
        },
...

Thanks again for spending your time to get this working, I really appreciate it.

When I try to compile, it got stuck on line 237: base64_encode(authValEncoded, authVal, (Username + String(":") + Password).length()); with error error: 'base64_encode' was not declared in this scope
Maybe I’m using the wrong version of Base64.h, but I can not get it working.