Support to measure more than 54612 Lux with the BH1750

[rradar]

Describe the problem you have/What new integration you would like

The esphome integration of the BH1750 Lux Sensor only allows to measure a maximum of 54612 Lux (in my tests). There is a possability (software wise) to measure more than 100000 Lux with this sensor at the costs of Measurement Time (MTreg) which can go up to a maximum of around 500 ms in this case (which is not bad at all!).

Please describe your use case for this integration and alternatives you've tried:

Like to measure outside with sun 🌞 which easily exceeds 54612 Lux

Additional context

There is a library and a little bit of context on this (German only) website:

Virtueller Modus:
RESOLUTION_AUTO_HIGH: Die Werte im MTreg ('Measurement Time'-Register) werden je nach Helligkeit automatisch so angepasst, dass eine maximalmögliche Auflösung und Messbereich erziehlt werden. Die messbaren Werte fangen von 0,11 lx und gehen bis über 100000 lx. (ich weis nicht, wie genau die Werte in Grenzbereichen sind, besonders bei hohen Werte habe ich da meine Zweifel. Die Werte scheinen jedoch weitgehend linear mit der steigenden Helligkeit zu wachsen.) Auflösung im Unteren Bereich ca. 0,13 lx, im mittleren 0,5 lx, im oberen etwa 1-2 lx. Die Messzeiten verlängern sich durch mehrfache Messungen und die Änderungen von Measurement Time (MTreg) bis max. ca. 500 ms.

http://s6z.de/cms/index.php/homeautomation-homecontrol/infrastruktur/aktorensensoren/offene-standard-systeme/i-c/15-umgebungslichtsensor-bh1750

[rradar]

Actually the source code already exists and is licensed under LGPL

Code can be found here: https://github.com/hexenmeister/AS_BH1750

It does also include a 'auto power down' beside supporting the measurement range from 0,11 to 100.000 lux.

[rradar]

Hey @OttoWinter sorry to interrupt but as I'm seeing you getting ready for the 1.14 release I wonder how hard this one here is to implement.

I'm driving my whole water and water-heating (solar) system with esphome and I'm just hardly lacking the feature to measure the radiated lux on the solar panel. The sensor is already in place but maxes out on 54612 lux.

[OttoWinter]

which can go up to a maximum of around 500 ms in this case (which is not bad at all!).

It would actually be the opposite - shorter measurement times allow for a higher range.

[rradar]

Could their be something tested with the new code already @OttoWinter ? I have a couple of esp's with bh1750 including one towards the sky and would be happy to contribute with testing.

esphome-dev is setup and ready but I don't know if I need to add any setting to the bh1750 component in the yaml to get shorter measurement times for higher range or if it is done automatically?

[OttoWinter]

You can test it by downloading this folder and placing the files under custom_components/bh1750 in your ESPHome config dir.

[rradar]

I did compile esphome 1.14.2 with the bh1750 custom component included and flashed it via ota (patching the running 1.13.6)

Still it maxes out at 54612.5.

I didn't see in the compiling logs that the custom component was used but as a folder __pycache__ was created inside the bh1750 folder while compiling it looks like it was accepted.

Now with the sensor in sun (partly cloudy today) the limit is better visible:

My yaml part:

sensor:
  - platform: bh1750
    name: "${upper_devicename} Panel Brightness"
    address: 0x23

[OttoWinter]

Ah sorry, forgot to mention: you need to supply the new measurement_time via config - the default is still the old one.

sensor:
  - platform: bh1750
    name: "${upper_devicename} Panel Brightness"
    address: 0x23
    # min: 31, default: 69, max: 254
    measurement_time: 31

[rradar]

Confirmed working @OttoWinter !

Is their any fixed upper/lower limit when having the measurement_time set to 31/254? I will try to update the docs correspondingly!

Thank's so much! This is a great improvement for this component! 🎉

[OttoWinter]

The max value for 31 would be 121556 lx and for 254 would be 14835 lx - as with any exposure time, longer exposure is good for low-light, short exposure is good for sunny scenes.

[rradar]

Updated docs: esphome/esphome-docs#440

[martin3000]

will this go into the normal release?

[rradar]

It need's to @martin3000! But first the pull request #997 needs to be fixed to pass the tests.

[martin3000]

@rradar how do these automated tests work?

[rradar]

@martin3000 travis does all the work:

He also says what to change to pass the test. In this case it's easy and some spaces in the right place should make the tests pass in the next run: