C20 Fan Control and Temperature Sensor
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November 14, 2009

The following information was provided by Andre Paquette.

Enable Fan:
  0x50, 0x02, 0x13, 0x27, 0x01, 0x00, 0x00, 0x00
 - returns '#'

Disable Fan:
  0x50, 0x02, 0x13, 0x27, 0x00, 0x00, 0x00, 0x00
 - returns '#'

Is Fan Enabled?
  0x50, 0x01, 0x13, 0x28, 0x00, 0x00, 0x00, 0x01
  - returns 0x00 for off and 0x01 for on, then '#'

Get temperature:
  0x50, 0x02, 0x12, 0x26, 0x00, 0x00, 0x00, 0x02
  - returns tempHi, then tempLo, then '#'
  - if both tempHi and tempLo are 127 then the sensor can't be found
  - use the following data sheet as a reference for how to convert the
      data into degrees C:
      
       http://datasheets.maxim-ic.com/en/ds/DS18B20.pdf

In the C20, the data from the temperature sensor is left-shifted 4 bits so that
it fills the 2-byte word from the most significant bit downward.