Monday, January 21, 2013

Heat Reactive Light

Change how the computer lights blink depending on the internal heat.


A PIC based light flasher that uses temperature as input and the status light on the computer as it's output. It has several states it can drive the two lights(Power/HDD): Brightness/Random, Blink synchronously, Pulse synchronously, Blink Alternating, Pulse Alternating, Brightness Both, Pulse/Random, Trigger(1 light on if it's hot, 2 on if it's really hot). A state is picked psuedo-randomly at startup based on the last 3 LSBs computed from the analog input of the thermistor. The states can be cycled through by pressing the reset button on the computer, and every other one is off(So it's easy to stop the blinking).

Source Code


  • PIC18F2550
  • 4.7 Kohms Resistor
  • 1 Kohm resistor
  • 220 Ohm resistor -- should match close to the thermistor, give or take for adjustment
  • 7.200 Oscillator(Could be about any, although speeds would need adjusted)
  • 3 sets of pins to hook up connectors (Salvaged from an old computer)
  • 300 Ohm Thermistor






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