info-MH-Z19.txt

MH-Z19 howto
https://pypi.org/project/mh-z19/

Wiring
5V on RPi and Vin on mh-z19
GND(0v) on RPi and GND on mh-z19
TxD and RxD are connected to cross between RPi and mh-z18

sudo python3 -m mh_z19


MH>-Z19 not woring:
On the RPi-3, the bluetooth device gets the UART and the serial port presented is a less capable (buggy) interface that doesn't work for the MH-Z CO2 sensors.

See this discussion: https://www.raspberrypi.org/forums/viewtopic.php?t=142112

I usually just use the disable-bt overlay. Or I use a USB serial adaptor.

How to use without root permission.
https://github.com/UedaTakeyuki/mh-z19/wiki/How-to-use-in-your-program.