#How to calculate ppm in air how to#
Now that we know the value of RL, let’s proceed on how to calculate the R o values in clean air. The connections are shown in the below table:Īfter connecting the hardware according to the circuit diagram, the Arduino MQ135 sensor setup should look something like below:Ĭalculating the R o Value of MQ135 Sensor Since the OLED Display module uses SPI communication, we have established an SPI communication between the OLED module and Arduino Nano. The Analog Out pin of the MQ-135 sensor is connected to the A0 pin of Arduino Nano. MQ-135 Gas Sensor and OLED Display module both are powered with +5V and GND. The circuit is very simple as we are only connecting the MQ-135 Sensor and OLED Display module with Arduino Nano. The complete schematics to connect MQ-135 Gas Sensor with Arduino is given below: Circuit Diagram to Interface MQ135 with Arduino So to measure the appropriate CO2 concentration values, you have to replace the 1KΩ resistor with a 22KΩ resistor. But if you track your PCB traces to find the value of your RL in the board, you can see a 1KΩ (102) load resistor. 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 KΩ. According to the MQ-135 datasheet, the load resistor value can range anywhere from 10KΩ to 47KΩ. This resistor changes its resistance value according to the concentration of gas. The load resistor RL plays a very important role in making the sensor work. The circuit diagram for the MQ-135 board is given below: In this project, we are using an MQ-135 sensor module to measure CO2 concentration in PPM.
MQ-135 sensor can either purchased as a module or just as a sensor alone. MQ-135 Gas Sensor is an air quality sensor for detecting a wide range of gases, including NH3, NOx, alcohol, benzene, smoke, and CO2. Useful when more than one module is used under SPI protocol Used for both I2C and SPIĭata pin of the module. The pins and its functions are explained in the table below:Īcts as the clock pin. You can also learn more about the basics of OLED display and its types by reading the linked article.
It can work on three different communications Protocols: SPI 3 Wire mode, SPI four-wire mode, and I2C mode. OLEDs are using the same technology as televisions, but have fewer pixels than in most of our TVs.įor this project, we are using a Monochrome 7-pin SSD1306 0.96” OLED display. A bright light is produced when an electric current is applied to these films.
#How to calculate ppm in air series#
OLED (Organic Light-Emitting Diodes) is a self light-emitting technology, constructed by placing a series of organic thin films between two conductors.