MH-Z 系列二氧化碳 CO2 传感器的 Arduino 实现（智能红外二氧化碳模块）C++

# MH-Z14A, MH-Z19B CO2 ... Module Arduino implementation for MH-Z CO2 sensors such as **MH-Z14A**, **MH-Z19B** and **MH-Z19C** (as I didn't find all info in one place). The sensor is available for ~20 bucks at the usual places. ## Implementation See example. > PPMuart: 602, PPMpwm: 595, Temperature: 23 ### Implementation details ``` C ppm = 5000 * (T_high - 2 ms) / (T_high + T_low - 4ms) ``` The implementation is mostly based on https://forum.arduino.cc/index.php?topic=525459.msg3587557#msg3587557 ## Usage By default the PWM range value is set to 5000 and there is no need to change anything in the class constructor (if the Cppm value is in the expected range 400-1000), otherwise you may want to test it with 2000 range value : ``` #include <MHZ.h> #define CO2_IN 9 #define MH_Z19_RX 10 #define MH_Z19_TX 11 MHZ co2(MH_Z19_RX, MH_Z19_TX, CO2_IN, MHZ19B); // here the range value is set to 5000 by default (RANGE_5K) MHZ co2(MH_Z19_RX, MH_Z19_TX, CO2_IN, MHZ19B, RANGE_2K); // here the range value is set to 2000 ``` ## Resources: Datasheet (MH-Z19B): http://www.winsen-sensor.com/d/files/infrared-gas-sensor/mh-z19b-co2-ver1_0.pdf Datasheet (MH-Z19C): https://pdf1.alldatasheet.com/datasheet-pdf/view/1303687/WINSEN/MH-Z19C.html More info about the sensor: https://revspace.nl/MHZ19 ## Further reading: - http://ihormelnyk.com/Page/mh-z19_co2_meter (russuian, but google translate does a good job) - https://geektimes.ru/post/285572/ - https://geektimes.ru/post/278178/