BME280 environment cookbook entry #107
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new cookbook entery fixing this issue: #89
| update_interval: 15s | ||
| - platform: template | ||
| name: "Altitude" | ||
| lambda: >- |
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use lambda: |- (it's safer for C++; I know the docs recommended >-, but that has been fixed in the edge version)
| - id: standard_sea_level_pressure_hpa | ||
| type: float | ||
| restore_state: no | ||
| initial_value: '1013.25' |
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Why use a global here? Globals have quite a overhead (well not too big, but certainly more than local variables). I think it would be simpler just to do something like this:
- platform: template
# ...
lambda: |-
float STANDARD_SEA_LEVEL_PRESSURE = 1013.25; // in hPa
return ((id(bme280_temperature).state + 273.15) / 0.0065) * ((powf(id(standard_sea_level_pressure) / id(bme280_pressure).state), 0.190234) - 1);There was a problem hiding this comment.
The idea was that this can be replaced by an Mqtt entry fetching the standard sea level pressure real time from either a stationary sensor in your network, or the web (via HA or something). I did not yet wrote that part as it involves a lot more (Mqtt, ha, etc).
| The first block of code (``globals``) contains the variable standard sea level pressure in hPa, which you should fill in for your location. | ||
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| The second block ``sensor`` starts with the normal bme280 sensor components ``temperature``, ``pressure``, and ``humidity`` with each their own id. | ||
| After the bme280 sensor, a :doc:`</esphomeyaml/components/sensor/template>` is defined to calculate the altitude in a lambda. |
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:doc:/esphomeyaml/components/sensor/template- remove the<>`, otherwise the link text is empty.
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| - `Relative humidity calculations <https://carnotcycle.wordpress.com/2012/08/04/how-to-convert-relative-humidity-to-absolute-humidity/>` | ||
| - `Altitude calculation <https://en.wikipedia.org/wiki/Atmospheric_pressure#Altitude_variation>` |
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| - `Altitude calculation <https://en.wikipedia.org/wiki/Atmospheric_pressure#Altitude_variation>` | |
| - `Altitude calculation <https://en.wikipedia.org/wiki/Atmospheric_pressure#Altitude_variation>`__ |
| Formula explanation | ||
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| - `Relative humidity calculations <https://carnotcycle.wordpress.com/2012/08/04/how-to-convert-relative-humidity-to-absolute-humidity/>` |
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| - `Relative humidity calculations <https://carnotcycle.wordpress.com/2012/08/04/how-to-convert-relative-humidity-to-absolute-humidity/>` | |
| - `Relative humidity calculations <https://carnotcycle.wordpress.com/2012/08/04/how-to-convert-relative-humidity-to-absolute-humidity/>`__ |
Fixed formatting, removed global variables as requested by OttoWinter
Yalm expamples were tested by Mihalski
Description:
New cookbook entry explaining how to get absolute humidity and altitude or sea level pressure from a BME280 sensor (or similar).
Related issue (if applicable): fixes this
Pull request in esphomeyaml with YAML changes (if applicable): none
Pull request in esphomelib with C++ framework changes (if applicable): none
Checklist:
nextis for changes and new documentation that will go public with the next esphomelib release. Fixes, changes and adjustments for the current release should be created againstcurrent.