This is an infrared to MQTT adapter for smartmeter based on libsml, running on ESP8266.
It is a quick and dirty build, but already transmitting data since some month now without any issue or hangup.
A simple IR diode (SFH309FA-5) with a resistor as voltage divider is connected to UART RX pin of ESP8266 module. (The resistor needs to be adjusted, to get squarewave signal on RX pin)
We only have an itron OpenWay 3HZ in our house. So, the repo is only tested for this meter, but should work with other smartmeters too.
I'm using an ESP01, because it is small and no more pins are needed. I've glued everything in a small plastic housing, so it can be hold by a magnet in front of the interface.
If you need some inspiration how to build a device, have a look in pictures folder.
esp-open-sdk and esp-open-rtos. You need to download and install these on your own, because it is not linked to this projekt.
https://github.com/SuperHouse/esp-open-rtos.git
or
https://github.com/ourairquality/oaq-esp-open-rtos.git
You need to edit Makefile to adapt your WIFI credentials and MQTT broker.
Compiling and upload to ESP is also on your side.
Hint: RX input of ESP is used for infrared. Remove programmer TX pin for normal operation, otherwise it won't receive anything from infrared diode.
All SML messages received via infrared will be paresed by libsml and pubilshed as a separate MQTT topic. Each MQTT value is a json string with value and unit:
{"value":123456.7,"unit":"Wh"}
https://wiki.volkszaehler.org/hardware/controllers/ir-schreib-lesekopf-rs232-ausgang
https://de.wikipedia.org/wiki/Smart_Message_Language
https://www.promotic.eu/en/pmdoc/Subsystems/Comm/PmDrivers/IEC62056_OBIS.htm