MMM-MHZ19

This is an extension for the MagicMirror².

It monitors CO2 level from MH-Z19 sensor and draws a chart for a few last hours.

Installation

1. Navigate into your MagicMirror's modules folder

2. Clone repository git clone https://github.com/awitwicki/MMM-MHZ19

3. Go to newly created directory

4. Execute npm install to install the node dependencies.

If you got error, try to execute npm install chartjs

5. Connect the MH-Z19 to your Raspberry Pi

Raspberry pi	MH-Z19
GPIO 17	PWM
Ground	GND
5V power	VIN

Using the module

Add it to the modules array in the config/config.js file:

modules: [
	...
	{
		module:  'MMM-MHZ19',
		position:  'top_left',
		config: {
			updateInterval:  100  //seconds
			}
	},
	...
]

Configuration options

Configurations properties

Property	Description
titleText	Type string, Default value Home weather
updateInterval	Type int, Default value 100, Minimal value 10, Wait interval between readings of BME280 sensor values in seconds

Developer Notes

For more details about BCM pin numbers check here

Dependencies

• python3 (should be installed on Raspberry Pi)

• RPi.GPIO (Python library, should be installed on Raspberry Pi )

Test MH-Z19 module

1. Navigate into your MagicMirror folder
2. Run .sh script ./modules/MMM-MHZ19/mh_z19.sh (If script doesn't run, add exec parameter to it) sudo chmod +x modules/MMM-MHZ19/mh_z19.sh.
3. Script should print sensor values like this 566 - that means CO2 PPM in air

Notice that MH-Z19 module can return small values (<400 PPM) continuously in a few seconds after hardware module was started (by connecting power voltage pin).

Thanks

MMM-DHT-Sensor module