sds011.rb

require "json"
require "net/http"

SDS011_DEV = "/dev/ttyUSB0"
FIREBASE_HOST = "airsensor.firebaseio.com"
AUTH_TOKEN = "B1K9LMmwtYR8EwXtSTztUUwhaC7IjE5HWUOOuSfk"

header, command, pm25l, pm25h, pm10l, pm10h, id1, id2, sum, tail = IO.read(SDS011_DEV, 10).unpack("CCCCCCCCCC")

if header == 0xAA && command == 0xC0 && (pm25l + pm25h + pm10l + pm10h + id1 + id2) % 256 == sum && tail == 0xAB
  pm25 = (pm25h * 256 + pm25l) / 10.0
  pm10 = (pm10h * 256 + pm10l) / 10.0

  data = JSON.generate({pm10: pm10, pm25: pm25, timestamp: {".sv": "timestamp"}})

  Net::HTTP.start(FIREBASE_HOST, 443, use_ssl: true) do |http|
    response = http.post("/measurements.json?auth=#{AUTH_TOKEN}", data)
    raise "Firebase communication error #{response.code}" if response.code != "200"
  end
else
  raise "SDS011 communication error"
end