I have sparkfun indoor air quality sensor CCS811 which needs to be interfaced with arduino. I have soldered wires on the sensors and connected with arduino. Have checked the connection with multimeter so that part works. But even using example code on library still I am not getting reading from sensor.


#include <Wire.h>

#include "SparkFunCCS811.h" 

#define CCS811_ADDR 0x5B //Default I2C Address
//#define CCS811_ADDR 0x5A //Alternate I2C Address

CCS811 mySensor(CCS811_ADDR);

void setup()
  Serial.println("CCS811 Basic Example");

  Wire.begin(); //Inialize I2C Harware

  //It is recommended to check return status on .begin(), but it is not
  CCS811Core::status returnCode = mySensor.begin();
  if (returnCode != CCS811Core::SENSOR_SUCCESS)
    Serial.println(".begin() returned with an error.");
    //while (1); //Hang if there was a problem.

void loop()
  //Check to see if data is ready with .dataAvailable()
  if (mySensor.dataAvailable())
    //If so, have the sensor read and calculate the results.
    //Get them later

    //Returns calculated CO2 reading
    Serial.print("] tVOC[");
    //Returns calculated TVOC reading
    Serial.print("] millis[");
    //Simply the time since program start

  delay(10); //Don't spam the I2C bus

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Things I tried:- 1) different combination of A4, A5 pins 2) 0x5A & 0x5B i2c address 3) using wake pin with ground 4) using 3.3 & 5V for powering sensor

What else needs to be done?

  • Don't supply the sensor with 5V. It's datasheet states 3.6V as maximum. You can destroy it with 5V
    – chrisl
    Jan 6, 2020 at 13:11
  • We cannot see, how you connected the sensor. A4 is the SDA pin, A5 is SCL. You need to connect them to the corresponding sensor pin. Also I2C is not made for long wires. Try to add strong pullup resistors to both lines (maybe 4.7kOhm).
    – chrisl
    Jan 6, 2020 at 13:13
  • @chrisl will keep them in mind. SDA is connected to A4 and SCL is A5 so not a problem, have uploaded the wiring image above. Wires are around 50cm long so I thought it will be fine. Pull up resistors on SDA & SCL line?
    – suu
    Jan 6, 2020 at 17:00
  • Yes, one pullup resistor for each of both lines. And 50cm is already rather long (I2C is made for communication between ICs on the same PCB or similar distances, so a few cm). Strong pullups might help, if your issue is related to this.
    – chrisl
    Jan 6, 2020 at 17:48
  • thanks for helping, the problem was on the soldering part so it's solved. Moreover, I have used i2c at 1m wire where I connected Arduino and LCD which worked. Just sharing my experience if it helps.
    – suu
    Jan 7, 2020 at 6:30

1 Answer 1


The problem was on the soldering part. SDA & 3.3V pin on sensor were slightly in contact. I modified it and started working fine.

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