7.3 KiB
BME280
Provides an Arduino library for reading and interpreting Bosch BME280 data.
Table of Contents
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void data(float& pressure, float& temp, float& humidity, bool metric = true, uint8_t p_unit = 0x0)
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float alt(bool metric = true, float seaLevelPressure = 101325)
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float alt(float pressure, bool metric = true, float seaLevelPressure = 101325)
Summary
Reads temperature, humidity, and pressure. Calculates altitude and dew point. Provides functions for english and metric. Also reads pressure in Pa, hPa, inHg, atm, bar, torr, N/m^2 and psi.
Installation
To use this library download the zip file, uncompress it to a folder named BME280. Move the folder to {Arduino Path}/libraries.
Usage
Include the library at the top of your Arduino script. #include <BME280>
Create a global or local variable. BME280 bme
In your start up call bme.begin().
Read the temperature, humidity, pressure, altitude and/or dew point.
float pres, temp, hum
bme.data(pres, temp, hum)
or
temp = bme.temp()
hum = bme.hum()
pres = bme.pres()
float altitude, dewPoint
altitude = bme.alt()
dewPoint = bme.dew()
Use setMode(0x01) to trigger a new measurement in forced mode. NOTE: It takes ~8ms to measure all values (temp, humidity & pressure) when using x1 oversampling (see datasheet 11.1). Thus a delay of >8ms should be used after triggering a measurement and before reading data to ensure that read values are the latest ones.
Methods
BME280(uint8_t tosr = 0x1, uint8_t hosr = 0x1, uint8_t posr = 0x1, uint8_t mode = 0x3, uint8_t st = 0x5, uint8_t filter = 0x0, bool spiEnable = false, uint8_t bme_280_addr = 0x76)
Constructor used to create the class. All parameters have default values. Return: None
* Temperature Oversampling Rate (tosr): uint8_t, default = 0x1
values: B000 = Skipped, B001 = x1, B010 = x2, B011 = x4, B100 = x8, B101/other = x16
* Humidity Oversampling Rate (hosr): uint8_t, default = 0x1
values: B000 = Skipped, B001 = x1, B010 = x2, B011 = x4, B100 = x8, B101/other = x16
* Pressure Oversampling Rate (posr): uint8_t, default = 0x1
values: B000 = Skipped, B001 = x1, B010 = x2, B011 = x4, B100 = x8, B101/other = x16
* Mode: uint8_t, default = Normal
values: Sleep = B00, Forced = B01 and B10, Normal = B11
* Standby Time (st): uint8_t, default = 1000ms
values: B000 = 0.5ms, B001 = 62.5ms, B010 = 125ms, B011 = 250ms, B100 = 250ms, B101 = 1000ms, B110 = 10ms, B111 = 20ms
* Filter: uint8_t, default = None
values: B000 = off, B001 = 2, B010 = 4, B011 = 8, B100/other = 16
* SPI Enable: bool, default = false
values: true = enable, false = disable
* BME280 Address: uint8_t, default = 0x76
values: any uint8_t
bool begin()
Method used at start up to initialize the class. Starts the I2C interface. Return: bool, true = success, false = failure (no device found)
void setMode(uint8_t mode)
Method to set the sensor mode. Sleep = B00, Forced = B01 and B10, Normal = B11. Set to B01 to trigger a new measurement when using forced mode.
float temp(bool celsius = true)
Read the temperature from the BME280 and return a float. Return: float = temperature
* Celsius: bool, default = true
values: true = return temperature in degrees Celsius, false = return
temperature in degrees Fahrenheit
float pres(uint8_t unit = 0x0)
Read the pressure from the BME280 and return a float with the specified unit. Return: float = pressure
* Unit: uint8_t, default = 0x0
values: B000 = Pa, B001 = hPa, B010 = Hg, B011 = atm, B100 = bar,
B101 = torr, B110 = N/m^2, B111 = psi
float hum()
Read the humidity from the BME280 and return a percentage as a float. Return: float = percent relative humidity
void data(float& pressure, float& temp, float& humidity, bool metric = true, uint8_t p_unit = 0x0)
Read the data from the BME280 with the specified units. Return: None, however, pressure, temp and humidity are changed.
* Pressure: float, reference
values: reference to storage float for pressure
* Temperature: float, reference
values: reference to storage float for temperature
* Humidity: float, reference
values: reference to storage float for humidity
* Metric: bool, default = true
values: true = meters, false = feet
* Pressure Unit: uint8_t, default = 0x0
values: B000 = Pa, B001 = hPa, B010 = Hg, B011 = atm, B100 = bar,
B101 = torr, B110 = N/m^2, B111 = psi
float alt(bool metric = true, float seaLevelPressure = 101325)
Read the data from the BME280 with the specified units and then calculate the altitude. Return: float = altitude
* Metric: bool, default = true
values: true = meters, false = feet
* Sea Level Pressure: float, unit = Pa, default = 101325
values: any float
float alt(float pressure, bool metric = true, float seaLevelPressure = 101325)
Calculate the altitude based on the pressure with the specified units. Return: float = altitude
* Pressure: float, unit = Pa
values: any float
* Metric: bool, default = true
values: true = meters, false = feet
* Sea Level Pressure: float, unit = Pa, default = 101325
values: any float
float dew(bool metric = true)
Read BME280 data and calculate the dew point with the specified units. Return: float = dew point
* Metric: bool, default = true
values: true = return temperature in degrees Celsius, false = return
temperature in degrees Fahrenheit
float dew(float temp, float hum, bool metric = true)
Calculate the dew point based on the temperature and humidity with the specified units. Return: float = dew point
* Temperature: float, unit = Celsius if metric is true, Fahrenheit if metric is false
values: any float
* Humidity: float, unit = % relative humidity
values: any float
* Metric: bool, default = true
values: true = return degrees Celsius, false = return degrees Fahrenheit
Contributing
- Fork the project.
- Create your feature branch:
git checkout -b my-new-feature - Commit your changes:
git commit -am 'Add some feature' - Push to the branch:
git push origin my-new-feature - Submit a pull request.
History
Jan 1, 2016 - Version 1.0.0 released. Sep 19, 2016 - Version 2.0.0 released (support for I2C and SPI).
Credits
Written by Tyler Glenn, 2016.
Special thanks to Mike Glenn for editing and reviewing the code.
License
GNU GPL, see License.txt