BME280 Complex measurement
Introduction
This page will take through all steps you need to make this sensor work with your microcontroller such as Arduino, ESP8266, Wemos.
I will be using I2C bus demanding only 4 wires for these pins: Vcc, GND, SCL, SDA.
Temperature sensor accuracy
| Min temp. [°C] | Max temp. [°C] | Temp. [°C] | Accuracy [°C] | Resolution [°C] |
| – | – | 25 | +-0.50 | 0.01 |
| 0 | 65 | – | +-1.00 | 0.01 |
| -20 | 0 | – | +-1.25 | 0.01 |
| -40 | -20 | – | +-1.50 | 0.01 |
Humidity sensor accuracy
| Min [%RH] | Max [%RH] | Temp. [°C] | Accuracy [%RH ] | Resolutio [%RH ] |
| 20 | 80 | 25 | +-3 | 0.01 |
| Min [hPa] | Max [hPa] | Min temp. [°C] | Max temp. [°C] | Accuracy [hPa] | Resolution [hPa] |
| 300 | 1100 | -20 | 20 | +-1.7 | 0.01 |
| 300 | 1100 | 0 | 65 | +-1.0 | 0.01 |
| 1100 | 1250 | 25 | 40 | +-1.5 | 0.01 |
| 700 | 900 | 25 | 40 | +-1.2 (relative) | 0.0.1 |
Pressure sensor accuracy
| Min [hPa] | Max [ hPa] | Min Temp. [°C] | Max Temp. [°C] | Accuracy [hPa] | Resolution [hPa] |
| 300 | 1100 | 0 | 65 | +-1.0 | 0.01 |
| 700 | 900 | 25 | 40 | +-0.12 | 0.01 |
Wiring
It is crucial to identify what pins on your development board can be used as SCL, SDA
IIR filter
Using IIR filter is crucial for a constant precise readings in a slow changing enviroment.
Code with fixed self heating problem
If you want to really use BME280 for some of your projects, please use this code.
BME280 has well known self heating problems causing rising temperature up to + 2°C.
/***************************************************************************
Lukas Pomykal 2019
BME280 reading example with advanced settings
www.lpomykal.cz
Adafruit library:
http://www.adafruit.com/products/2651
***************************************************************************/
#include <Adafruit_BME280.h>
#define BME280_Address (0x76) // usually (0x76), but might be (0x77)
#define seaLevelPressure (1013.25) // sea level pressure at your location
#define delayTime (60000) //It is necessary to read values in a longer interval so the sensor will not heat up itself, read every minute (60000 ms = 60 s = 1 min)
Adafruit_BME280 bme; // I2C
void setup() {
Serial.begin(9600);
Serial.println("BME280 test");
if (!bme.begin(BME280_Address)) { // If sensor has not been found (could not been initialized)
Serial.println("BME280 has not been found!");
Serial.println("Please check your wiring or BME280_Address");
while (1);
}
//BME280 weather station settings corresponding to datasheet
bme.setSampling(Adafruit_BME280::MODE_FORCED, // Force reading after delayTime
Adafruit_BME280::SAMPLING_X1, // Temperature sampling set to 1
Adafruit_BME280::SAMPLING_X1, // Pressure sampling set to 1
Adafruit_BME280::SAMPLING_X1, // Humidity sampling set to 1
Adafruit_BME280::FILTER_OFF // Filter off - immediate 100% step response
);
}
void loop() {
// Only needed in forced mode! In normal mode, you can remove the next line.
bme.takeForcedMeasurement(); // has no effect in normal mode
Serial.print("Temperature = ");
Serial.print(bme.readTemperature());
Serial.println(" °C");
Serial.print("Pressure = ");
Serial.print(bme.readPressure() / 100.0F);
Serial.println(" hPa");
Serial.print("Altitude = ");
Serial.print(bme.readAltitude(seaLevelPressure));
Serial.println(" m");
Serial.print("Humidity = ");
Serial.print(bme.readHumidity());
Serial.println(" %RH");
Serial.println();
delay(delayTime);
}
