Fan and temperature controller with LCD

The module uses an LM35 sensor for measuring the temperature, it is a pre-calibrated IC with output voltage linearly-proportional to the Centigrade temperature. This is read directly by the internal AVR ADC, and turned into actual degrees with a simple calculation. The fan is powered by an PWM output, giving it variable speed. Set points for the fan and alarm can be adjusted and is saved to EEPROM.


LCD unit driven by a computer parallel port

This very simple module is driven purely by a computer parallel (printer) port. Almost no external components are needed; a few capacitors for voltage stabilization, a trimmer for the contrast adjustment and a resistor for the LED back-light. All communication is done directly over the parallel port data lines. The LCD is powered by an external 5 V power supply. It can’t be placed too far from the computer though since the recommended max length of a parallel cable is 15 ft.


Module heartbeat monitor with 15 inputs and LCD

As I started putting more and more modules into my rack box project, the previous monitoring module quickly ran out of inputs. I needed to build something bigger and better. I realized that using LEDs to show module status just wasn’t practical as the number of inputs increased. So this unit shows the module statuses on an LCD display instead, and has 15 inputs.


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