Guide for BME680 Environmental Sensor with Arduino (Gas, Temperature, Humidity, Pressure)

The BME680 is an environmental digital sensor that measures gas, pressure, humidity and temperature. In this guide you’ll learn how to use the BME680 sensor module with the Arduino board. The sensor communicates with a microcontroller using I2C or SPI communication protocols.

You’ll learn how to wire the sensor to the Arduino board, install the required libraries and use a simple sketch to display the sensor readings in the Serial Monitor.

Introducing BME680 Environmental Sensor Module

The BME680 is an environmental sensor that combines gas, pressure, humidity and temperature sensors. The gas sensor can detect a broad range of gases like volatile organic compounds (VOC). For this reason, the BME680 can be used in indoor air quality control.

BME680 Measurements

The BME680 is a 4-in-1 digital sensor that measures:

• Temperature
• Humidity
• Barometric pressure
• Gas: Volatile Organic Compounds (VOC) like ethanol and carbon monoxide

Gas Sensor

The BME680 contains a MOX (Metal-oxide) sensor that detects VOCs in the air. This sensor gives you a qualitative idea of the sum of VOCs/contaminants in the surrounding air – it is not specific for a specific gas molecule.

MOX sensors are composed of a metal-oxide surface, a sensing chip to measure changes in conductivity, and a heater. It detects VOCs by adsorption of oxygen molecules on its sensitive layer. The BME680 reacts to most VOCs polluting indoor air (except CO2).

When the sensor comes into contact with the reducing gases, the oxygen molecules react and increase the conductivity across the surface. As a raw signal, the BME680 outputs resistance values. These values change due to variations in VOC concentrations:

• Higher concentration of VOCs » Lower resistance
• Lower concentration of VOCs » Higher resistance

The reactions that occur on the sensor surface (thus, the resistance) are influenced by parameters other than VOC concentration like temperature and humidity.

Relevant Information Regarding Gas Sensor

The gas sensor gives you a qualitative idea of VOCs gasses in the surrounding air. So, you can get trends, compare your results and see if the air quality is increasing or decreasing. To get precise measurements, you need to calibrate the sensor against knows sources and build a calibration curve.

When you first get the sensor, it is recommended to run it for 48 hours after start collecting “real” data. After that, it is also recommend to run the sensor for 30 minutes before getting a gas reading.

BME680 Accuracy

Here’s the accuracy of the temperature, humidity and pressure sensors of the BME680:

BME680 Operation Range

The following table shows the operation range for the temperature, humidity and pressure sensors for the BME680.

BME680 Pinout

Here’s the BME680 Pinout:

BME680 Interface

The BME680 supports I2C and SPI Interfaces.

BME680 I2C

To use I2C communication protocol, use the following pins:

BME680 SPI

To use SPI communication protocol, use the following pins:

Parts Required

To complete this tutorial you need the following parts:

• BME680 sensor module
• Arduino Uno – read Best Arduino Starter Kits
• Breadboard
• Jumper wires

You can use the preceding links or go directly to MakerAdvisor.com/tools to find all the parts for your projects at the best price!

Schematic – Arduino with BME680

The BME680 can communicate using I2C or SPI communication protocols.

Arduino with BME680 using I2C

Follow the next schematic diagram to wire the BME680 to the Arduino using the I2C pins.

Arduino with BME680 using SPI

Alternatively, you may want to use SPI communication protocol instead. In that case, follow the next schematic diagram to wire the BME680 to the Arduino using the SPI pins.

Installing the BME680 Library

To get readings from the BME680 sensor module we’ll use the Adafruit_BME680 library. Follow the next steps to install the library in your Arduino IDE:

Open your Arduino IDE and go to Sketch > Include Library > Manage Libraries. The Library Manager should open.

Search for “adafruit bme680 ” on the Search box and install the library.

Installing the Adafruit_Sensor Library

To use the BME680 library, you also need to install the Adafruit_Sensor library. Follow the next steps to install the library in your Arduino IDE:

Go to Sketch > Include Library > Manage Libraries and type “Adafruit Unified Sensor” in the search box. Scroll all the way down to find the library and install it.

After installing the libraries, restart your Arduino IDE.

Code Arduino – Reading BME680 Gas, Pressure, Humidity and Temperature

To read gas, pressure, temperature, and humidity we’ll use a sketch example from the library.

After installing the BME680 library, and the Adafruit_Sensor library, open the Arduino IDE and, go to File > Examples > Adafruit BME680 Library > bme680async.

/***
  Read Our Complete Guide: https://RandomNerdTutorials.com/bme680-sensor-arduino-gas-temperature-humidity-pressure/
  
  Designed specifically to work with the Adafruit BME680 Breakout ----> http://www.adafruit.com/products/3660 These sensors use I2C or SPI to communicate, 2 or 4 pins are required to interface. Adafruit invests time and resources providing this open source code, please support Adafruit and open-source hardware by purchasing products from Adafruit! Written by Limor Fried & Kevin Townsend for Adafruit Industries. BSD license, all text above must be included in any redistribution
 ***/

#include <Wire.h>
#include <SPI.h>
#include <Adafruit_Sensor.h>
#include "Adafruit_BME680.h"

/*#define BME_SCK 13
#define BME_MISO 12
#define BME_MOSI 11
#define BME_CS 10*/

#define SEALEVELPRESSURE_HPA (1013.25)

Adafruit_BME680 bme; // I2C
//Adafruit_BME680 bme(BME_CS); // hardware SPI
//Adafruit_BME680 bme(BME_CS, BME_MOSI, BME_MISO, BME_SCK);

void setup() {
  Serial.begin(115200);
  while (!Serial);
  Serial.println(F("BME680 async test"));

  if (!bme.begin()) {
    Serial.println(F("Could not find a valid BME680 sensor, check wiring!"));
    while (1);
  }

  // Set up oversampling and filter initialization
  bme.setTemperatureOversampling(BME680_OS_8X);
  bme.setHumidityOversampling(BME680_OS_2X);
  bme.setPressureOversampling(BME680_OS_4X);
  bme.setIIRFilterSize(BME680_FILTER_SIZE_3);
  bme.setGasHeater(320, 150); // 320*C for 150 ms
}

void loop() {
  // Tell BME680 to begin measurement.
  unsigned long endTime = bme.beginReading();
  if (endTime == 0) {
    Serial.println(F("Failed to begin reading :("));
    return;
  }
  Serial.print(F("Reading started at "));
  Serial.print(millis());
  Serial.print(F(" and will finish at "));
  Serial.println(endTime);

  Serial.println(F("You can do other work during BME680 measurement."));
  delay(50); // This represents parallel work.
  // There's no need to delay() until millis() >= endTime: bme.endReading()
  // takes care of that. It's okay for parallel work to take longer than
  // BME680's measurement time.

  // Obtain measurement results from BME680. Note that this operation isn't
  // instantaneous even if milli() >= endTime due to I2C/SPI latency.
  if (!bme.endReading()) {
    Serial.println(F("Failed to complete reading :("));
    return;
  }
  Serial.print(F("Reading completed at "));
  Serial.println(millis());

  Serial.print(F("Temperature = "));
  Serial.print(bme.temperature);
  Serial.println(F(" *C"));

  Serial.print(F("Pressure = "));
  Serial.print(bme.pressure / 100.0);
  Serial.println(F(" hPa"));

  Serial.print(F("Humidity = "));
  Serial.print(bme.humidity);
  Serial.println(F(" %"));

  Serial.print(F("Gas = "));
  Serial.print(bme.gas_resistance / 1000.0);
  Serial.println(F(" KOhms"));

  Serial.print(F("Approx. Altitude = "));
  Serial.print(bme.readAltitude(SEALEVELPRESSURE_HPA));
  Serial.println(F(" m"));

  Serial.println();
  delay(2000);
}

View raw code

How the Code Works

Continue reading this section to learn how the code works, or skip to the Demonstration section.

Libraries

The code starts by including the needed libraries: the wire library to use I2C, the SPI library (if you want to use SPI instead of I2C), the Adafruit_Sensor and Adafruit_BME680 libraries to interface with the BME680 sensor.

#include <Wire.h>
#include <SPI.h>
#include <Adafruit_Sensor.h>
#include "Adafruit_BME680.h"

SPI communication

We prefer to use I2C communication protocol with the sensor. However, the code is prepared if you want to use SPI. You just need to uncomment the following lines of code that define the SPI pins.

/*#define BME_SCK 13
#define BME_MISO 12
#define BME_MOSI 11
#define BME_CS 10*/

Sea level pressure

A variable called SEALEVELPRESSURE_HPA is created.

#define SEALEVELPRESSURE_HPA (1013.25)

This variable saves the pressure at the sea level in hectopascal (is equivalent to milibar). This variable is used to estimate the altitude for a given pressure by comparing it with the sea level pressure. This example uses the default value, but for accurate results, replace the value with the current sea level pressure at your location.

I2C

This example uses I2C communication protocol by default. The following line creates an Adafruit_BME680 object called bme on the Arduino I2C pins: D5 (SCL), D4 (SDA).

Adafruit_BME680 bme; // I2C

To use SPI, you need to comment this previous line and uncomment the following line.

//Adafruit_BME680 bme(BME_CS, BME_MOSI, BME_MISO, BME_SCK); // software SPI

setup()

In the setup() start a serial communication.

Serial.begin(115200);

Init BME680 Sensor

Initialize the BME680 sensor:

if (!bme.begin()) {
  Serial.println(F("Could not find a valid BME680 sensor, check wiring!"));
  while (1);
}

Set up the following parameters (oversampling, filter and gas heater) for the sensor.

// Set up oversampling and filter initialization
bme.setTemperatureOversampling(BME680_OS_8X);
bme.setHumidityOversampling(BME680_OS_2X);
bme.setPressureOversampling(BME680_OS_4X);
bme.setIIRFilterSize(BME680_FILTER_SIZE_3);
bme.setGasHeater(320, 150); // 320*C for 150 ms

To increase the resolution of the raw sensor data, it supports oversampling. We’ll use the default oversampling parameters, but you can change them.

• setTemperatureOversampling(): set temperature oversampling.
• setHumidityOversampling(): set humidity oversampling.
• setPressureOversampling(): set pressure oversampling.

These methods can accepts one of the following parameters:

• BME680_OS_NONE: turn off reading;
• BME680_OS_1X
• BME680_OS_2X
• BME680_OS_4X
• BME680_OS_8X
• BME680_OS_16X

The BME680 sensor integrates an internal IIR filter to reduce short-term changes in sensor output values caused by external disturbances. The setIIRFilterSize() method sets the IIR filter. It accepts the filter size as a parameter:

• BME680_FILTER_SIZE_0 (no filtering)
• BME680_FILTER_SIZE_1
• BME680_FILTER_SIZE_3
• BME680_FILTER_SIZE_7
• BME680_FILTER_SIZE_15
• BME680_FILTER_SIZE_31
• BME680_FILTER_SIZE_63
• BME680_FILTER_SIZE_127

The gas sensor integrates a heater. Set the heater profile using the setGasHeater() method that accepts as arguments:

• the heater temperature (in degrees Centigrade)
• the time the heater should be on (in milliseconds)

We’ll use the default settings: 320 ºC for 150 ms.

loop()

In the loop(), we’ll get measurements from the BME680 sensor.

First, tell the sensor to start an asynchronous reading with bme.beginReading(). This returns the time when the reading would be ready.

// Tell BME680 to begin measurement.
unsigned long endTime = bme.beginReading();
if (endTime == 0) {
  Serial.println(F("Failed to begin reading :("));
  return;
}
Serial.print(F("Reading started at "));
Serial.print(millis());
Serial.print(F(" and will finish at "));
Serial.println(endTime);

Then, call the endReading() method to end an asynchronous reading. If the asynchronous reading is still in progress, block until it ends.

if (!bme.endReading()) {
  Serial.println(F("Failed to complete reading :("));
  return;
}

After this, we can get the readings as follows:

• bme.temperature: returns temperature reading
• bme.pressure: returns pressure reading
• bme.humidity: returns humidity reading
• bme.gas_resistance: returns gas resistance

Serial.print(F("Temperature = "));
Serial.print(bme.temperature);
Serial.println(F(" *C"));

Serial.print(F("Pressure = "));
Serial.print(bme.pressure / 100.0);
Serial.println(F(" hPa"));

Serial.print(F("Humidity = "));
Serial.print(bme.humidity);
Serial.println(F(" %"));

Serial.print(F("Gas = "));
Serial.print(bme.gas_resistance / 1000.0);
Serial.println(F(" KOhms"));

Serial.print(F("Approx. Altitude = "));
Serial.print(bme.readAltitude(SEALEVELPRESSURE_HPA));
Serial.println(F(" m"));

For more information about the library methods, take a look at the Adafruit_BME680 Class Reference.

Demonstration

Upload the code to your Arduino board. Go to Tools > Board and select the Arduino board you’re using. Go to Tools > Port and select the port your board is connected to. Then, click the upload button.

Open the Serial Monitor at a baud rate of 115200, press the on-board RST button. The sensor measurements will be displayed.