Introduction

Build up a simple environmental monitor station with this multi-function environment sensor! Based on the combination of CCS811+BME280 chip, this module features high accuracy, IIC interface and fast Measurement. The BME280 can provide temperature and humidity compensation for CCS811 to improve the whole accuracy to a certain extent. It can be used to detect temperature, humidity, barometric pressure, altitude, TVOC and eCO2.

CCS811 air quality sensor uses AMS's unique micro-hot plate technology. Compared with conventional gas sensors, it has lower power consumption, shorter preheating time, and smaller size. The internally integrated ADC and MCU allow it to collect and process data, and return via I2C.

BME280 is an environmental sensor that combines temperature sensor, humidity sensor and barometer in one board. It has high precision, multiple functions, small size, etc. The sensor offers ±0.5℃ temperature error and ±2%RH humidity error. It provides very stable performance within the detection temperature range. Besides, the offset temperature coefficient is ±1.5 Pa/K, equiv. to ±12.6 cm at 1 °C temperature change.

warning_yellow.png NOTE: The chip has stretched the clock in I2C. So, it may be not compatible with some controllers, such as Raspberry Pi.

The following table shows the effects of carbon dioxide and TVOC on the human body.

Carbon Dioxide (PPM) Effect on Human TVOC Concentration (PPB) Effect on Human
<500 Normal <50 Normal
500-1000 A little uncomfortable 50-750 Anxious,uncomfortable
1000-2500 Tired 750-6000 depressive, headache
2500-5000 Unhealthy >6000 headache and other nerve problems

Applications

Specification

SEN0335 SIZE

CCS811 Parameter:

Board Overview

SEN0335SVG

Num Label Description
1 VCC +
2 GND -
3 SCL IIC clock line
4 SDA IIC data line
5 INT Interrupt pin: interrupt in low level
6 WAKE Switch pin: awake in low level / sleep in high level
7 RST Reset pin: reset in low level

Tutorial

This sensor adopts Gravity I2C interface, so it is easy to use. Connect the sensor to Uno baord as the way shown below.

The product warm-up time is short, accurate readings can be made quickly once powered up. The read time can be shortened by setting the environmental baseline (the baseline acquisition and setup method are explained below; for more details about baseline, go to the end of the wikipage to find the related document).

warning_yellow.png NOTE: Please run the sensor for 48hours when using it for the first time.

Requirements

 /*****************CCS811**********************/
 /**
   * @brief Judge if the data can be read 
   * @return true when the reading is successful, false means it fails to read.
   */
  bool checkDataReady();

    /**
   * @brief Set environment parameter 
   * @param temperature Input temperature value, unit: centigrade, range (-40~85℃)
   * @param humidity    Input humidity value, unit: RH, range (0~100)
   */
  void setInTemHum(float temperature, float humidity);

  /**
   * @brief Measurement parameter configuration 
   * @param cycle:eClosed      :Idle (Measurements are disabled in this mode)
   *              eCycle_1s    :Constant power mode, IAQ measurement every second
   *              eCycle_10s   :Pulse heating mode IAQ measurement every 10 seconds
   *              eCycle_60s   :Low power pulse heating mode IAQ measurement every 60 seconds
   *              eCycle_250ms :Constant power mode, sensor measurement every 250ms 
   */
  void setMeasCycle(eCycle_t cycle);

  /**
   * @brief Measurement parameter configuration
   * @param thresh:    0 for Interrupt mode operates normally; 
   *                   1 for interrupt mode only asserts the nINT signal (driven low) if the new
   * @param interrupt: 0 for Interrupt generation is disabled; 
   *                   1 for the nINT signal is asserted (driven low) when a new sample is ready in
   * @param mode:      in typedef enum eDRIVE_MODE_t
   */
  void setMeasurementMode(uint8_t thresh, uint8_t interrupt, eDRIVE_MODE_t mode);

  /**
   * @brief Get the current carbon dioxide concentration 
   * @return current carbon dioxide concentration, unit:ppm
   */
  uint16_t  getCO2PPM();

  /**
   * @brief Get current TVOC concentration
   * @return Return current TVOC concentration, unit: ppb
   */
  uint16_t getTVOCPPB();

  /**
   *@brief get the current baseline number
   *@return a Hexadecimal number of the current baseline number
   */
  uint16_t readBaseLine();

  /**
   *@brief write a baseline number into register
   *@param a Hexadecimal number get from getBaseLine.ino
   */
  void writeBaseLine(uint16_t baseLine);


 /*****************BME280**********************/
   /**
   * @brief getTemperature Get temperature
   * @return Temprature in Celsius
   */
  float getTemperature();

  /**
   * @brief getPressure Get pressure
   * @return Pressure in pa
   */
  uint32_t getPressure();

  /**
   * @brief getHumidity Get humidity
   * @return Humidity in percent
   */
  float getHumidity();

  /**
   * @brief calAltitude Calculate altitude
   * @param seaLevelPressure Sea level pressure
   * @param pressure Pressure in pa
   * @return Altitude in meter
   */
  float calAltitude(float seaLevelPressure, uint32_t pressure);

Connection Diagram

SEN0335CONNECT

1. Get Baseline

Why should we get the baseline?

Why should we get the baseline? Because once get it, we can show the air quality quickly after the sensor warm-up by inputting the baseline. Otherwise, it will cost a long time to read correctly when startup in polluted air.

During the first week of running the sensor, it is recommended to save a new baseline every 24 hours. After 1 week of operation, it can be saved every 1-28 days

warning_yellow.png NOTE:

  • Please place it in a fresh air environment (20 minutes or more) to obtain the baseline.
  • Different sensors, different measurement cycles have different baselines.
/*!
 * @file getBaseLine.ino
 * @brief Put the module in clear air and work a few minutes, wait for baseline doing not change 
 * @n Experiment phenomenon: get
 *
 * @copyright    Copyright (c) 2010 DFRobot Co.Ltd (https://www.dfrobot.com)
 * @licence     The MIT License (MIT)
 * @author [LuoYufeng](yufeng.luo@dfrobot.com)
 * @version  V0.1
 * @date  2019-07-19
 * @https://github.com/DFRobot/DFRobot_CCS811
 */
#include "DFRobot_CCS811.h"


/*
 * IIC address default 0x5A, the address becomes 0x5B if the ADDR_SEL is soldered.
 */
//DFRobot_CCS811 sensor(&Wire, /*IIC_ADDRESS=*/0x5A);
DFRobot_CCS811 sensor;

void setup(void)
{
    Serial.begin(115200);
    /*Wait for the chip to be initialized completely, and then exit*/
    while(sensor.begin() != 0){
        Serial.println("failed to init chip, please check if the chip connection is fine");
        delay(1000);
    }
    /**
     * @brief Set measurement cycle
     * @param cycle:in typedef enum{
     *                  eClosed,      //Idle (Measurements are disabled in this mode)
     *                  eCycle_1s,    //Constant power mode, IAQ measurement every second
     *                  eCycle_10s,   //Pulse heating mode IAQ measurement every 10 seconds
     *                  eCycle_60s,   //Low power pulse heating mode IAQ measurement every 60 seconds
     *                  eCycle_250ms  //Constant power mode, sensor measurement every 250ms
     *                  }eCycle_t;
     */
    sensor.setMeasCycle(sensor.eCycle_250ms);
}
void loop() {
    if(sensor.checkDataReady() == true){
        /*!
         * @brief Set baseline
         * @return baseline in clear air
         */
        Serial.println(sensor.readBaseLine(), HEX);

    } else {
        Serial.println("Data is not ready!");
    }
    //delay cannot be less than measurement cycle
    delay(1000);
}

Expected Results

After a while, the baseline reaches to a stable value.

Result1

2. Get Data

Input the baseline value to the function sensor.writeBaseLine();If you don't want to set the baseline, please disable this function in the sample program. The sensor will automatically calibrate the baseline, but it would be a pretty long process. after the function uploaded to UNO, open the serial port monitor to check the carbide dioxide concentration and TVOC concentration.

/*!
 * @file readData.ino
 * @brief Read the concentration of carbon dioxide and TVOC
 * @n Experiment phenomenon: read data every 0.5s, and print it out on serial port. 
 *
 * @copyright    Copyright (c) 2010 DFRobot Co.Ltd (https://www.dfrobot.com)
 * @licence     The MIT License (MIT)
 * @author [LuoYufeng](yufeng.luo@dfrobot.com)
 * @version  V0.1
 * @date  2019-07-19
 * @https://github.com/DFRobot/DFRobot_CCS811
 */
#include "DFRobot_CCS811.h"

/*
 * IIC address default 0x5A, the address becomes 0x5B if the ADDR_SEL is soldered.
 */
//DFRobot_CCS811 sensor(&Wire, /*IIC_ADDRESS=*/0x5A);
DFRobot_CCS811 sensor;

void setup(void)
{
    Serial.begin(115200);
    /*Wait for the chip to be initialized completely, and then exit*/
    while(sensor.begin() != 0){
        Serial.println("failed to init chip, please check if the chip connection is fine");
        delay(1000);
    }
    /**
     * @brief Set measurement cycle
     * @param cycle:in typedef enum{
     *                  eClosed,      //Idle (Measurements are disabled in this mode)
     *                  eCycle_1s,    //Constant power mode, IAQ measurement every second
     *                  eCycle_10s,   //Pulse heating mode IAQ measurement every 10 seconds
     *                  eCycle_60s,   //Low power pulse heating mode IAQ measurement every 60 seconds
     *                  eCycle_250ms  //Constant power mode, sensor measurement every 250ms
     *                  }eCycle_t;
     */
    sensor.setMeasCycle(sensor.eCycle_250ms);
}
void loop() {
    if(sensor.checkDataReady() == true){
        Serial.print("CO2: ");
        Serial.print(sensor.getCO2PPM());
        Serial.print("ppm, TVOC: ");
        Serial.print(sensor.getTVOCPPB());
        Serial.println("ppb");

    } else {
        Serial.println("Data is not ready!");
    }
    /*!
     * @brief Set baseline
     * @param get from getBaseline.ino
     */
    sensor.writeBaseLine(0x447B);
    //delay cannot be less than measurement cycle
    delay(1000);
}

Expected Results

Result2

3. Concentration Alarm

Input the baseline value to the function sensor.writeBaseLine(); Upload it to UNO, when the CO2 concentration moves from the current range (low, medium, high) to another range (more than 50 ppm), an interruption is generated and the current CO2 value will be printed.

NOTE: This example requires the INT pin of the sensor to be connected to the corresponding interrupt pin on the main board (in the sample, D2 of UNO is selected).

AVR Series Interrupt Pin and Interrupt Number

328 Mainboards: Uno, Nano, Mini... Mega2560 32u4 Mainboards: Leonardo...
Interrupt Pin D2, D3 D2, D3, D21, D20, D19, D18 D3, D2, D0, D1, D7
Interrupt Number 0, 1 0, 1, 2, 3, 4, 5 0, 1, 2, 3 ,4
/*!
 * @file setInterrupt.ino
 * @brief Set interrupt parameter, when CO2 concentration range changes, get an interrupt
 * @n Experiment phenomenon: read data every 1s, and print it out on serial port.
 *
 * @copyright    Copyright (c) 2010 DFRobot Co.Ltd (https://www.dfrobot.com)
 * @licence     The MIT License (MIT)
 * @author [LuoYufeng](yufeng.luo@dfrobot.com)
 * @version  V1.0
 * @date  2019-07-13
 * @https://github.com/DFRobot/DFRobot_Sensor
 */
#include "DFRobot_CCS811.h"

volatile  int8_t GPIO1TRIG = 0;

/*
 * IIC address default 0x5A, the address becomes 0x5B if the ADDR_SEL is soldered.
 */
//DFRobot_CCS811 sensor(&Wire, /*IIC_ADDRESS=*/0x5A);
DFRobot_CCS811 sensor;

void setup(void)
{
    Serial.begin(115200);
    /*wait for the chip to be initialized completely, and then exit*/
    while(sensor.begin() != 0){
        Serial.println("failed to init chip, please check if the chip connection is fine");
        delay(1000);
    }
    attachInterrupt(0, interrupt, RISING);
    sensor.setMeasurementMode(1, 1, sensor.eMode4);
    /**
     * @brief Set interrupt thresholds 
     * @param lowToMed: interrupt triggered value in range low to middle 
     * @param medToHigh: interrupt triggered value in range middle to high 
     */
    sensor.setThresholds(1500,2500);
}
void loop() {
    if(GPIO1TRIG == 1){
        Serial.println("CO2 range has changed");
        Serial.print("CO2: ");
        Serial.print(sensor.getCO2PPM());
        Serial.print("ppm, TVOC: ");
        Serial.print(sensor.getTVOCPPB());
        Serial.println("ppb");
        delay(1000);
    }
    GPIO1TRIG = 0;
    Serial.print("CO2: ");
    Serial.print(sensor.getCO2PPM());
    Serial.print("ppm, TVOC: ");
    Serial.print(sensor.getTVOCPPB());
    Serial.println("ppb");
    sensor.writeBaseLine(0x847B);
    delay(1000);
}


void interrupt(){
  GPIO1TRIG = 1;
}

Expected Results

When you blow air to the sensor, the range of CO2 concentration changes, which results in an interruption; when the gas concentration decreases, there is also an interruption.

Result3

4. BME280 Read Data

Note:please check the IIC address of BME280 in the program before using. Chip initialization will fail when the hardware IIC address is not the same as the address in the codes.

Run the codes, then the related data will be printed.

/*!
 * raed_data_i2c.ino
 *
 * Download this demo to test read data from bme280, connect sensor through IIC interface
 * Data will print on your serial monitor
 *
 * Copyright   [DFRobot](http://www.dfrobot.com), 2016
 * Copyright   GNU Lesser General Public License
 *
 * version  V1.0
 * date  12/03/2019
 */

#include "DFRobot_BME280.h"
#include "Wire.h"

typedef DFRobot_BME280_IIC    BME;    // ******** use abbreviations instead of full names ********

BME   bme(&Wire, 0x76);   // select TwoWire peripheral and set sensor address

#define SEA_LEVEL_PRESSURE    1015.0f

// show last sensor operate status
void printLastOperateStatus(BME::eStatus_t eStatus)
{
  switch(eStatus) {
  case BME::eStatusOK:    Serial.println("everything ok"); break;
  case BME::eStatusErr:   Serial.println("unknow error"); break;
  case BME::eStatusErrDeviceNotDetected:    Serial.println("device not detected"); break;
  case BME::eStatusErrParameter:    Serial.println("parameter error"); break;
  default: Serial.println("unknow status"); break;
  }
}

void setup()
{
  Serial.begin(115200);
  bme.reset();
  Serial.println("bme read data test");
  while(bme.begin() != BME::eStatusOK) {
    Serial.println("bme begin faild");
    printLastOperateStatus(bme.lastOperateStatus);
    delay(2000);
  }
  Serial.println("bme begin success");
  delay(100);
}

void loop()
{
  float   temp = bme.getTemperature();
  uint32_t    press = bme.getPressure();
  float   alti = bme.calAltitude(SEA_LEVEL_PRESSURE, press);
  float   humi = bme.getHumidity();

  Serial.println();
  Serial.println("======== start print ========");
  Serial.print("temperature (unit Celsius): "); Serial.println(temp);
  Serial.print("pressure (unit pa):         "); Serial.println(press);
  Serial.print("altitude (unit meter):      "); Serial.println(alti);
  Serial.print("humidity (unit percent):    "); Serial.println(humi);
  Serial.println("========  end print  ========");

  delay(1000);
}

Expected Results

SEN0335RESULTS4

FAQ

Q: Why the sensor init failed and the serial monitor printed "device not detected"?
A: Check whether the IIC address in the codes is the same as the sensor address.

More

DFshopping_car1.png Get Multi-function Environmental Module - CCS811+BME280 from DFRobot Store or DFRobot Distributor.

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