Temperature monitor raspberry pi DS18B20 sensor

gettemp.rb

require "json"

def temp()
	number = Dir.glob('/sys/bus/w1/devices/*').count-1
	if number>0 
	@temperatures = Array.new

	Dir.glob('/sys/bus/w1/devices/*').each_with_index {|folder, index|
		values = Hash.new 
		foldername = folder.gsub('/sys/bus/w1/devices/','')
		if foldername[0,2]=='28'
			gettemp = IO.readlines("/sys/bus/w1/devices/#{foldername}/w1_slave") [1]
			temp = gettemp[29,32]
			temp = temp.insert(2, '.')
			temp = temp.gsub("\n","")
			values[:id] = foldername
			values[:value] = temp
			values[:time] = Time.now.strftime "%d/%m/%Y %H:%M:%S"
			@temperatures[index] = values
		end		
	}
	end
	return @temperatures
end

puts temp()
puts temp().to_json

links

https://learn.adafruit.com/downloads/pdf/adafruits-raspberry-pi-lesson-11-ds18b20-temperature-sensing.pdf
https://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/temperature/
http://www.modmypi.com/blog/ds18b20-one-wire-digital-temperature-sensor-and-the-raspberry-pi
http://www.sbprojects.com/projects/raspberrypi/temperature.php
https://www.raspberrypi.org/forums/viewtopic.php?p=518859#p518859