Read MH-Z14 CO2 sensor readings

mh-z14.rb

#!/usr/bin/env ruby
# Read MH-Z14 CO2 sensor readings connected via serial port

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem "rubyserial", "0.6.0"
end

require "rubyserial"

s = Serial.new "/dev/tty.wchusbserialfd130"

loop do
  s.write([0xff, 0x01, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x79].pack("c*"))

  response_b = s.read(9)
  response = response_b.unpack "CC S> cccc C"
  pp response

  concentration = response[2]
  pp concentration

  sleep 5
end