#Deal: self-calibrated CO2 sensor MH-Z19 UART output + PWM up to 5000ppm

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Last updated on 11 February 2019 2 h 04 min

The MH-Z19 from Winsen is a self-calibrated sensor that measures the concentration of CO2 in the atmosphere. It is a digital sensor capable of delivering a directly readable digital value expressed in ppm. The MH-Z19 has a PWM type digital output. The signal is proportional to the concentration of CO2 in the atmosphere (see below).

Presentation of the self-calibrated MH-Z19 CO2 sensor

The MH-Z19 is a self-calibrated sensor, ie the measurement sent by the sensor does not require any mathematical treatment. In other words, the CO2 content expressed in ppm (parts per million) is recovered. The MH-Z19 has a PWM output and a UART digital interface (serial port). For this tutorial, we will already start by exploiting the PWM output.

Measuring range0 – 5000ppm
Precision± 50ppm+5%
Power supply3.6 ~ 5.5 VDC
Current< 18 mA
Numerical outputsUART and PWM
Heat time3 minutes
Working temperature0 ~ 50 ℃
Working humidity0 – 95% (without condensation)
Dimensions33 mm×20 mm×9 mm (L×W×H)
Lifetime annonced> 5 years

The PWM signal is proportional to the CO2 concentration.

It will therefore be necessary to measure the time during which the signal remains at the high level. Then, the following formula allows to deduce the CO2 rate.

  • Cppm represents the concentration of CO2 in the atmosphere in ppm
  • Th, the time during which the signal remained high
  • Tl, the time during which the signal has remained low

For a 0-5000ppm sensor, simply replace 2000 by 5000 in the formula. The complete documentation is available here.

Tutorials and DIY projects based on the MH-Z19

CO2 detector MH-Z19 deals

  • All prices mentioned above are in United States dollar.
  • This product is available at AliExpress, Banggood, Ebay, Amazon.com.
  • At aliexpress.com you can purchase MH-Z19 infrared co2 sensor for co2 monitor for only $18.40, which is 39% less than the cost in Ebay ($30.11).
  • The lowest price of Infrared CO2 Sensor Module Parts for Indoor Air Quality Monitor 0-5000PPM MH-Z19 was obtained on 17 February 2020 2 h 01 min.