Add edl21 component for SML-based smart meters

[mtdcr]

Description:

This PR integrates EDL21 compatible smart meters as used in Germany. These smart meters use SML protocol messages to transmit various „OBIS“ values.

Pull request with documentation for home-assistant.io: home-assistant/home-assistant.io#11325

Example entry for configuration.yaml:

sensor:
  - platform: edl21
  - serial_port: socket://10.2.3.4:7750

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly. Update and include derived files by running python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

If the code does not interact with devices:

• Tests have been added to verify that the new code works.

[mtdcr]

Rebased and updated pysml dependency from 0.0.1 to 0.0.2.

[DavidMStraub]

Thanks for this very nice component! I tested it and it works very well! For the documentation that is still to be added, I suggest to mention also

• which hardware (IR diode) is known to work
• how to set up ser2net to transmit serial over the network (thanks for helping me with this)

A useful feature in my opinion would be to customize the update interval. For instance, my smart meter reports the power to 0.01 W and energy to 0.1 mWh precision every second, which is really excessive. Every 10 or 30 seconds would be more than enough for me (and fill the history less). I think this could be achieved easily by adding a scan_interval config option and adding a homeassistant.util.Throttle decorator to the EDL21Entity.update_telegram method.

[mtdcr]

• which hardware (IR diode) is known to work

Already done, see home-assistant/home-assistant.io#11325.

• how to set up ser2net to transmit serial over the network (thanks for helping me with this)

I'm not sure about this. It is a feature of pyserial in general and applies to many more components supported by Home Assistant.

Every 10 or 30 seconds would be more than enough for me (and fill the history less). I think this could be achieved easily by adding a scan_interval config option and adding a homeassistant.util.Throttle decorator to the EDL21Entity.update_telegram method.

I'll look into it.

[DavidMStraub]

FYI, I tested adding

from datetime import timedelta
from homeassistant.util import Throttle

MIN_TIME_BETWEEN_UPDATES = timedelta(seconds=30)

# ...

    @Throttle(MIN_TIME_BETWEEN_UPDATES)
    def update_telegram(self, telegram: dict) -> bool:
        # ...

and it works as expected. When using a config option for the update interval (rather than hard-coding it), I guess one cannot use the decorator but can patch the method after instantiating the EDL21Entity.

[mtdcr]

Thank you, David! Would you mind creating a PR on my branch, to preserve your authorship?

I'd prefer 60 seconds, however, because that would match the interval used by the volkszaehler component. dsmr doesn't do any throttling, AFAICS. Are there any other smart meter components in HA?

[balloob]

Looks great. One final comment 🎉

[mtdcr]

Thank you for your reviews! I hope to have addressed everything by now.

[MartinHjelmare]

Looks good!

Just a question.

[MartinHjelmare]

What kind of time is this?

[mtdcr]

It's an optional timestamp which indicates when the measurement was performed. My device doesn't use it, though.

[MartinHjelmare]

Ok 👍

Absolute timestamps are ok and they should be UTC.