I had bought 3 MQ-135 gas sensors on AliExpress to test if it is possible to measure CO2 with them. Suman. If you have no experience with soldering you better leave the 1K resistor and change the value in the library. Before you start the programming, first of all, make sure you download the necessary libraries; otherwise, you wont be able to display anything on your Oled display module. 
Can I ask, if the voltage is 3.3 V, do I need to modify the library somwhere? But when breath out right in front of sensor, suddenly the reading rises up closing to 170-220 PPM. ppm = 1/1 000 000 = 10-6. Again, thanks for your knowledge and patience. Pad: Phn ng dn in 2 u ca mt l via. Will it work if I dont make the changes in the resistor? Thanks for your effort. Thanks for the excellent writeup. i was run that program but i get a error message like that gasSensor was not declared in this scope and error in this line of code please help me to solve this float ppm = gasSensor.getPPM(); I just noticed that the following was on 1 line in my example: #include MQ135.h You can see the red circle on the picture where I mention that the resistor is wrong. For that, open the Arduino IDE and go to Sketch < Include Library < Manage Libraries. I have this model (see link 1 below), how do I know the RLOAD value of this model? Used for both I2C and SPI, Data pin of the module. Now scroll down and replace the ATMOCO2 value with the current Atmospheric CO2 that is 411.29. Hey rob, Carbon dioxide is a key greenhouse gas and responsible for about three-quarters of emissions. 32 61 gives about 52ppm/value Then, create an Adafruit display instance with the width and height defined earlier with the SPI communication protocol. Hi, I would like to know how do you replace the load resistor from 1K ohms to 22 K ohms. As you can probably tell, I have near zero hardware experience, so I want to thank you again for taking the time to explain. I currently use 10.0 as RLOAD, because thats what the library I use came with (I am using the library in link 2 below, is that a good one?). So basically we will be making the Carbon Dioxide Parts per Million Meter. // display.display() is NOT necessary after every single drawing command, // unless that's what you wantrather, you can batch up a bunch of, // drawing operations and then update the screen all at once by calling. And in the last, call the display() method to display the text on OLED Display. I see that my RL is 1K ohm. Gii thiu ESP32 vi ADC ni
Hi sir, so float MQ135::getResistance() {
The more measurement you take the better it will be. Upload the code to Arduino and the following text will be displayed on the OLED display module. and you also need to change the formula in the library. Now inside the setup() function, initialize the Serial Monitor at a baud rate of 9600 for debugging purposes. The screw on the back is only to adjust the on/off point of the digital output. For that, connect the Arduino to the laptop, select the Board and Port, and hit the upload button. File You have entered an incorrect email address! I have not yet calibrated still by burning it for 24 hours. This will calibrate the sensor with the reference of 397.13ppm (ATMOCO2 line 42 .h file) return ((1023. Do you have any why I am not getting any meaningful reading from it? // the library initializes this with an Adafruit splash screen. This resistor changes its resistance value according to the concentration of gas. If you had to power it down after the burn-in then calibration can be done after 1 hour power-on. Im wondering if it could be due to one of the following: I used a normal resistor and soldered it to the board. Submitted by Ihaiz on Thu, 05/06/2021 - 13:48. But nothing change. meaning that the equation should be changed to this instead of 5-1? The circuit diagram for the MQ-135 board is given below: The load resistor RL plays a very important role in making the sensor work. After that, define the Arduino pin where the MQ-135 sensor is connected. If I do, then (1) do I have to change anything in the .h file and (2) do I need to recalibrate? The PPM values are calculated using the Load resistor, R0, and reading from the analog pin. After installing the libraries to Arduino IDE, start the code by including the needed libraries files. Th vin: https://github.com/GeorgK/MQ135. I think it will better to change that value to 403, as 397 was the lowest CO2 a few years ago. int val = analogRead(_pin); Bn s thy trn mch module, nh sn xut hn in tr RL ; 1K (102). And also say how to find the RZERO Robot And also, for the schemetic diagram of the gas sensor, do you solder the resistor to both analog and ground wire? With 15 different sizes, aluform enclosures provide customers a wide range of potential uses. Save my name, email, and website in this browser for the next time I comment. CO2 Concentration, CO2 PPM, or CO2 Levels using MQ135 Sensor & Arduino, Connect the SDA pin of the OLED with the pin number A4, Connect the SCK pin of the OLED with the pin number A5, Connect the VCC pin of the OLED with the 5V of the Arduino, Connect the ground pin of the OLED with the ground of the Arduino, Now click on files and in files click on examples and in examples select, /**************************************************************************, This is an example for our Monochrome OLEDs based on SSD1306 drivers, ------> http://www.adafruit.com/category/63_98, This example is for a 128x32 pixel display using I2C to communicate. 3 pins are required to interface (two I2C and one reset). // Then update coordinates of each flake // If snowflake is off the bottom of the screen // Reinitialize to a random position, just off the top, Upload the code to Arduino and the following text will be displayed on the OLED display module. I just have a noob question, After i have burned it for 24 hrsHow I will get the RZero value?? After that, set the text size and text colour using the setTextSize() and setTextColor(). I think it will better to change that value to 403, as 397 was the lowest CO2 a few years ago. Then define the SPI communication pins where OLED Display is connected. Ci t ti Sketch => Include Library => Manage Libraries nh cc th vin khc trn Arduino. We use cookies to ensure that we give you the best experience on our website. Theo datasheet ca MQ135 th RL c th iu chnh t 10K n 47K. After these 24 hours I checked the values measured with the above little test program. #define RLOAD 22.0 If you already know how to interface the SDD1306 I2C Oled display module with the Arduino then you can jump to the end. * RLOAD; in tr RL c vai tr rt quan trng n hot ng ca module sensor. As the MQ135 is heated the outside temperature/humidity does not give very high variation. So first download the MQ-135 Library, then preheat the sensor for 24 hours before reading the Ro values. Mch iu khin: In my room s the real ppm was about 770 ppm according to my NETATMO. // Library will draw what it can and the rest will be clipped. We can also install the library manually from zip file. The next day I have tested the same with another MQ-135, but the results were about the same.
Link 2: https://github.com/ViliusKraujutis/MQ135. change: The Arduino sends outthe following output to the serial port. This is normal. A bright light is produced when an electric current is applied to these films. the sensor needs around 24-48 hours to burn in als0 you are able to calibrate it with the screw on the back, https://c.76.my/Malaysia/mq-135-air-quality-detector-sensor-module-arduino-iot-littlecraft-1611-20-littlecraft@7.jpg. MQ-135 Gas Sensor is an air quality sensor for detecting a wide range of gases, including NH3, NOx, alcohol, benzene, smoke, and CO2. Tng quan v kin trc ARM v h vi iu khin STM32, PIC18F4550 LCD2004 DS1307 RTC, cm bin DHT22 trn CCS C, Module o in AC a Nng Giao Tip UART PZEM004T, KIT STM32F4 Discovery Bi 5: B nh thi (TIMER), [Su tm] Vi lu khi thit k mch in nhiu lp, [Arduino IDE] Lp trnh STM32F103C8T6 vi DHT11 hin th LCD, 11 mo layout PCB cho tn hiu tc cao high speed, Pht hin im khng ca in xoay chiu vi PIC16F877A, https://technologyitemsforcollege.blogspot.com, BST1: TIMER 0 PIC16F877A vi trnh bin dch XC8, https://www.facebook.com/pages/category/Health---Wellness-Website/Vital-flow-reviews-102135748499657/, o tc ng c dng encoder vi Arduino, Mt s khi nim cn bn v GPIO ca Vi iu khin push-pull v open-drain, Thit t Digital Pins nh l INPUT, INPUT_PULLUP, v OUTPUT, [Arduino]Giao tip nhiu cm bin nhit DS18B20, Chn chn mn hnh lm Slave khi giao tip SPI, in tr ti: Thay i c (2kOm -> 47kOm), Cng sut tiu th ca heater: Nh hn 800mW, Nng pht hin ca mt s cht: 10 300 ppm NH3, 10 1000 ppm Benzen, 10 300 ppm Alcol. // drawing commands to make them visible on screen! Now we will learn how to connect and code an I2C OLED display with an Arduino microcontroller board and we will also learn how to write a simple code to display a message on your OLED screen. These resolutions are valid if the scale is lineair, but the scale is logirithmic. In this project, we are using an MQ-135 sensor module to measure CO2 concentration in PPM. The next morning ppm was down to 500 according to the NETATMO, but the arduino showed a ppm of 600. Then open your serial monitor and wait for some time (preheat process), then you'll see the final data. Do I need to remove the on-board resistor and replace it with a 22K one (and I dont have the means to do that), or can I use breadboard to just add a 22K resistor? I change the RZERO to 819 and the arduino also showed 500. } Then, define the OLED width and height. -My arduino uno 5V pin cant provide enough power for the MQ135. And may i know how to set the RO since every-time the value is varies. Lowest CO2 now a days will be 403 in the forests, if you live in a city with high car pollution your lowest CO2 will be around 410-425. You can also learn more about the basics of OLED display and its types by reading the linked article. Then in the next line, define the position where the text starts using the setCursor(x,y) method. These libraries can be downloaded from the Library Manager in the Arduino IDE and install it from there. Will resistance add up to 23K if I do that? After a 24 hour burn-in you can directly do the calibration. The datasheet recommends that you calibrate the detector for 100ppm NH3 or 50ppm Alcohol concentration in air and use a value of load resistance (RL) of about 20 K. The global average atmospheric carbon dioxide in 2019 was 409.8 parts per million and in October-2020 it is 411.29. Breathing on them gave very little difference, as the values were only doubled to 28 61 103, With these values you can say that the first two are useless to measure CO2 as the difference is to little.