Freelance Journey


Smart-AC Controller

2017.11-2018.0, Commissioned by Honeywell International Inc,

The controller system adjusts AC’s motor power to the temperature and pressure, according to a pre-defined set of logic that performs differently under the 4 modes of the system: Auto, Manm, Vent and Test. 

Input: temperature and pressure from the AC’s bumper

Output: the resistance of digital potentiometers

The system reports the parameters in real time on the screen. It also allows mode-switching through the screen. Some buttons, toggles, and text boxes are available only under certain mode. If temperature or pressure reaches abnormal level, the system also reports error statement on the screen, and triggers auto adjustment.

All the data and operation are saved to a SD card at the frequency of minute.


Tech Rider:

  • Arduino Mega
  • 7″ LCD Touch Screen (link)
  • Temperature sensor, Pressure sensor, Digital Potentiometer, SD card


  • Arduino(C++)
  • Processing(Java) as Simulation

Smart-AC Controller Documentation

Smart-AC Controller Host Computer Simulation