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Rework the BME280 docs to be in line with our standards

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docs/en/modules/bme280.md
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# bme280 module # BME280 module
The bme280 module provides simple interface to BME280/BMP280 temperature/air presssure/humidity sensor. This module provides a simple interface to [BME280/BMP280 temperature/air presssure/humidity sensors](http://www.bosch-sensortec.com/bst/products/all_products/bme280) (Bosch Sensortec).
|Method|Description| Note that you must call [`init()`](#bme280init) before you can start reading values!
|---------------|-------------|
|[init()](#init)|Initializes the module and sets the pin configuration.|
|[temp()](#temp)|Reads the sensor and returns the temperature in celsius as an integer multiplied with 100.|
|[baro()](#baro)|Reads the sensor and returns the air temperature in hectopascals as an integer multiplied with 1000.|
|[humi()](#humi)|Reads the sensor and returns the air relative humidity in percents as an integer multiplied with 100.|
|[startreadout()](#startreadout)|Starts readout (turns the sensor into forced mode).|
|[qfe2qnh()](#qfe2qnh)|For given altitude converts the air pressure to sea level air pressure.|
|[altitude()](#altitude)|For given air pressure and sea level air pressure returns the altitude in meters as an integer multiplied with 100.|
|[dewpoint()](#dewpoint)|For given temperature and relative humidity returns the dew point in celsius as an integer multiplied with 100.|
## Methods ## bme280.altitude()
###init() For given air pressure and sea level air pressure returns the altitude in meters as an integer multiplied with 100, i.e. altimeter function.
####Description #### Syntax
Initialize module. Initialization is mandatory before read values. `bme280.altitude(P, QNH)`
####Syntax #### Parameters
`init(sda, scl)` - `P` measured pressure
- `QNH` current sea level pressure
`init(sda, scl, temp_oss, press_oss, humi_oss, power_mode, inactive_duration, IIR_filter)` #### Returns
altitude in meters of measurement point
####Parameters ## bme280.baro()
* `sda` - SDA pin
* `scl` - SCL pin Reads the sensor and returns the air temperature in hectopascals as an integer multiplied with 1000 or `nil` when readout is not successful.
* (optional) `temp_oss` - Controls oversampling of temperature data. Default oversampling is 16x. Current temperature is needed to calculate the air pressure so temperature reading is performed prior reading pressure data. Second returned variable is therefore current temperature.
* (optional) `press_oss` - Controls oversampling of pressure data. Default oversampling is 16x.
* (optional) `humi_oss` - Controls oversampling of humidity data. Default oversampling is 16x #### Syntax
* (optional) `sensor_mode` - Controls the sensor mode of the device. Default sensor more is normal. `bme280.baro()`
* (optional) `inactive_duration` - Controls inactive duration in normal mode. Default inactive duration is 20ms.
* (optional) `IIR_filter` - Controls the time constant of the IIR filter. Default fitler coefficient is 16. #### Parameters
none
#### Returns
- `P` air pressure in hectopascals multiplied by 1000
- `T` temperature in celsius as an integer multiplied with 100
## bme280.dewpoint()
For given temperature and relative humidity returns the dew point in celsius as an integer multiplied with 100.
#### Syntax
`bme280.dewpoint(H, T)`
#### Parameters
- `H` relative humidity in percent multiplied by 1000.
- `T` temperate in celsius multiplied by 100.
#### Returns
dew point in celsisus
## bme280.humi()
Reads the sensor and returns the air relative humidity in percents as an integer multiplied with 100 or `nil` when readout is not successful.
Current temperature is needed to calculate the relative humidity so temperature reading is performed prior reading pressure data. Second returned variable is therefore current temperature.
#### Syntax
`bme280.humi()`
#### Parameters
none
#### Returns
- `H` last relative humidity reading in % times 1000
- `T` temperature in celsius as an integer multiplied with 100
## bme280.init()
Initializes module. Initialization is mandatory before read values.
#### Syntax
`bme280.init(sda, scl, [temp_oss, press_oss, humi_oss, power_mode, inactive_duration, IIR_filter])`
#### Parameters
- `sda` - SDA pin
- `scl` - SCL pin
- (optional) `temp_oss` - Controls oversampling of temperature data. Default oversampling is 16x.
- (optional) `press_oss` - Controls oversampling of pressure data. Default oversampling is 16x.
- (optional) `humi_oss` - Controls oversampling of humidity data. Default oversampling is 16x
- (optional) `sensor_mode` - Controls the sensor mode of the device. Default sensor more is normal.
- (optional) `inactive_duration` - Controls inactive duration in normal mode. Default inactive duration is 20ms.
- (optional) `IIR_filter` - Controls the time constant of the IIR filter. Default fitler coefficient is 16.
|`temp_oss`, `press_oss`, `humi_oss`|Data oversampling| |`temp_oss`, `press_oss`, `humi_oss`|Data oversampling|
|-----|-----------------| |-----|-----------------|
@ -71,10 +116,10 @@ Using forced mode is recommended for applications which require low sampling rat
|3|8| |3|8|
|**4**|**16**| |**4**|**16**|
####Returns #### Returns
`nil` initialization has failed (no sensor connected?), `2` sensor is BME280, `1` sensor is BMP280 `nil` if initialization has failed (no sensor connected?), `2` if sensor is BME280, `1` if sensor is BMP280
### Example #### Example
```lua ```lua
alt=320 -- altitude of the measurement place alt=320 -- altitude of the measurement place
@ -109,117 +154,43 @@ bme280.startreadout(0, function ()
end) end)
``` ```
**-** [Back to index](#index) ## bme280.qfe2qnh()
###temp()
####Description
Reads the sensor and returns the temperature in celsius as an integer multiplied with 100.
####Syntax
`temp()`
####Parameters
none
####Returns
* `T` - temperature in celsius as an integer multiplied with 100 or `nil` when readout is not successful.
* `t_fine` - temperature measure used in pressure and humidity compensation formulas (generally no need to use this value)
**-** [Back to index](#index)
###baro()
####Description
Reads the sensor and returns the air temperature in hectopascals as an integer multiplied with 1000 or `nil` when readout is not successful.
Current temperature is needed to calculate the air pressure so temperature reading is performed prior reading pressure data. Second returned variable is therefore current temperature.
####Syntax
`baro()`
####Parameters
none
####Returns
* `P` - air pressure in hectopascals multiplied by 1000.
* `T` - temperature in celsius as an integer multiplied with 100.
**-** [Back to index](#index)
###humi()
####Description
Reads the sensor and returns the air relative humidity in percents as an integer multiplied with 100 or `nil` when readout is not successful.
Current temperature is needed to calculate the relative humidity so temperature reading is performed prior reading pressure data. Second returned variable is therefore current temperature.
####Syntax
`humi()`
####Parameters
none
####Returns
* `H` - last relative humidity reading in % times 1000.
* `T` - temperature in celsius as an integer multiplied with 100.
**-** [Back to index](#index)
###startreadout()
Starts readout (turns the sensor into forced mode). After the readout the sensor turns to sleep mode.
####Syntax
`startreadout(delay, callback)`
####Parameters
* `delay` - sets sensor to forced mode and calls the `callback` (if provided) after given number of milliseconds. For 0 the default delay is set to 113ms (sufficient time to perform reading for oversampling settings 16x). For different oversampling setting please refer to BME280 Final Datasheet - Appendix B: Measurement time and current calculation.
* `callback` - if provided it will be invoked after given `delay`. The sensor reading should be finalized by then so.
####Returns
`nil`
**-** [Back to index](#index)
###qfe2qnh()
Description
For given altitude converts the air pressure to sea level air pressure. For given altitude converts the air pressure to sea level air pressure.
####Syntax #### Syntax
`qfe2qnh(P, altitude)` `bme280.qfe2qnh(P, altitude)`
####Parameters #### Parameters
* `P` - measured pressure - `P` measured pressure
* `altitude` - altitude in meters of measurement point - `altitude` altitude in meters of measurement point
####Returns #### Returns
* `QNH` - sea level pressure sea level pressure
**-** [Back to index](#index) ## bme280.startreadout()
Starts readout (turns the sensor into forced mode). After the readout the sensor turns to sleep mode.
###altitude() #### Syntax
####Description `bme280.startreadout(delay, callback)`
For given air pressure and sea level air pressure returns the altitude in meters as an integer multiplied with 100, i.e. altimeter function.
####Syntax #### Parameters
`altitude(P, QNH)` - `delay` sets sensor to forced mode and calls the `callback` (if provided) after given number of milliseconds. For 0 the default delay is set to 113ms (sufficient time to perform reading for oversampling settings 16x). For different oversampling setting please refer to [BME280 Final Datasheet - Appendix B: Measurement time and current calculation](http://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BME280_DS001-11.pdf#page=51).
- `callback` if provided it will be invoked after given `delay`. The sensor reading should be finalized by then so.
####Parameters #### Returns
* `P` - measured pressure `nil`
* `QNH` - current sea level pressure
####Returns ## bme280.temp()
* `altitude` - altitude in meters of measurement point
**-** [Back to index](#index) Reads the sensor and returns the temperature in celsius as an integer multiplied with 100.
###dewpoint() #### Syntax
####Description `bme280.temp()`
For given temperature and relative humidity returns the dew point in celsius as an integer multiplied with 100.
####Syntax #### Parameters
`dewpoint(H, T)` none
####Parameters #### Returns
* `H` - relative humidity in percent multiplied by 1000. - `T` temperature in celsius as an integer multiplied with 100 or `nil` when readout is not successful
* `T` - temperate in celsius multiplied by 100. - `t_fine` temperature measure used in pressure and humidity compensation formulas (generally no need to use this value)
####Returns
* `dewpoint` - dew point in celsisus.
**-** [Back to index](#index)