RAD [Ruby Arduino] servo thermometer demo from RubyConf 2008

gistfile1.rbx

class ServoDemo < ArduinoSketch
 
  external_vars :sensor_position => "int, 0", :servo_amount => "int, 0"
 
  output_pin 15, :as => :myTemp, :device => :onewire
  output_pin 14, :as => :my_servo, :device => :servo
  serial_begin
 
  @hi_byte    = "0, int"
  @lo_byte    = "0, int"
  @device_crc = int
  @t_reading  = int
  @sign_bit   = int
  @tc_100     = int


  def loop
    servo_refresh
    start_temp_conversion
    toggle 13
    delay 750
    toggle 13           
    get_temp_data
    print_temperature
    adjust_dial
  end
 
  def get_temp_data
    until myTemp.reset do       # reset bus, verify its clear and high
      delay 500
    end
    myTemp.skip                 # listen up!
    myTemp.write 0xBE, 1        # send me your data conversions
    
    @lo_byte = myTemp.read      # get irst byte
    @hi_byte = myTemp.read      # get second byte
    
    7.times { @device_crc = myTemp.read } # get next 6 bytes, drop them on floor
                                          # next byte the ninth byte is the CRC
    
                            # DS18B20 brings data temperature back as 12 bits
                            # in degrees centigrade with 4 bits fractional, that is 
                            # each bit s 1/16 of a degreeC
    
    @t_reading  =   build_int @hi_byte, @lo_byte
    @sign_bit   =   bit_and @t_reading, 0x8000
    @t_reading  =   twos_comp @t_reading   if @sign_bit  # negative
   
    @tc_100     = (6 * @t_reading) + (@t_reading / 4)   #multiply by (100 * 0.0625) or 6.25
  end       
 
  def start_temp_conversion
    until myTemp.reset do # reset bus, verify its clear and high
      delay 500
    end
    myTemp.skip           # "listen up - everybody!"
    myTemp.write 0x44, 1  # temperature sensors, strta conversion
  end
 
 def adjust_dial
   temp_dec = ((@tc_100 / 100) * 10 ) + ((@tc_100 % 100)/10)
   temp_position = (temp_dec - 200) * (255.0 / 300)   
   serial_print "servo: "
   serial_println temp_position
   
   my_servo.position temp_position
  end
 
 def print_temperature
   serial_print (@tc_100 / 100)             # separate off the whole
   serial_print  "."
   serial_println ((@tc_100 % 100)/10)      # and fractional portions
 end

 
end