Record CO2 ppm value from MH-Z19b via UART.

• retrieve ppm value and publish it to MQTT topic
• subscribe MQTT topic and append min/max/median/avg to google spreadsheet

Follow the instruction to enable Spreadsheet API.

Create service account and download its credentials in JSON.

• Create spreadsheet and
• share it with the service account.
• Create sheet1

To build it for Raspberry Pi

GOOS=linux GOARCH=arm GOARM=7 go build

Run mosquitto

sudo apt install mosquitto
sudo systemctl start mosquitto

./co2-monitor sniff

./co2-monitor recordSpreadsheet -record-interval 300 -spreadsheet-id your-spreadsheet-id

where your-spreadsheet-id is in the URL of Google spreadsheet. https://docs.google.com/spreadsheets/d/{your-spread-sheet-id}/....