MH-Z19 (PWM) CO2 sensor support package

[mbz4]

This item focuses on building a support package for the MH-Z19 CO2 sensor using PWM protocol.

Testing w/ this PWM Async library:

No results so far:

Tried several wiring configs:

Useful docs here:

• MH-Z19B @revspace.nl
• interesting multi-lib
• winsen official mh-z19b user manual

Pin	Definition
Vin	Vin
GND	GND
Vo	Analog output (0.4～2 V) or (0~2.5V)
PWM	PWM
HD	HD (zero calibration, low level lasting for over 7s under low level is effective)
Rx	UART (RXD) TTL Level data input
Tx	UART (TXD) TTL Level data output