The MH-Z19C carbon dioxide gas sensor (hereinafter referred to as the sensor) is a general-purpose intelligent small sensor that uses the principle of non-dispersive infrared (NDIR) to detect the presence of C02 in the air.Built-in temperature compensation: simultaneously has serial output, PWM output, easy to use. The sensor is a high-performance sensor made by closely combining mature infrared absorption gas detection technology with sophisticated optical circuit design and sophisticated circuit design.Detection gas:carbon dioxidePower supply voltage:DC (5.00.1) VAverage current:Less than 40mA (@5V power supply)current:125 to (@5V power supply)Interface level:3.3v(compatible with 5v)Measuring range:400-5000PPM optionalOutput signal:serial UART(TL level 3.3V)Warm-up time:1minResponse time:T90 Less than 120sWorking temperature:-10-50Working humidity:0-95%RH(no condensation)Pin description:Vin:Power +(in)GND:power supply-(GND)PWM:PWMHd:HD (zero calibration, low level is effective for more than 7 seconds)Rx:UART (RXD) TTL level data inputTx:UART (TXD) TTL level data outputOutput method:PWM outputAssume the measurement range is 400-2000ppmCO2:Concentration output range: 400-2000ppmPeriod:1004ms5%High level output at the beginning of the cycle: 2ms (theoretical value)Central period:1000ms5%Low level output at the end of the period: 2ms (theoretical value)Calculation formula for obtaining current CO2 concentration value by PWM: Cppm=2000X (TH-2ms)/(TH+TL-4ms)Cppm: CO2 concentration value calculated by the unit of ppmTH: the time when the output is high level in one output cycleTL: the time when the output is low in one output cycleDue to different product batches, the appearance may vary, which does not affect the use.Colour:As ShownMaterial:PC+Aluminum Alloy