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Overheating alarm

This board monitors its sensor and shows the temperature in °C. An alarm sounds if the temperature goes over a threshold configured in the source code. The brightness of the display is reduced depending on the ambient light so that energy is conserved and the display will not appear too bright at night.

The board demonstrates multiplexed LED displays ( all 24 segments are driven from the µC even though it’s only a 20-pin part).

The switch toggles between showing the current temperature and showing the extreme temperatures since power-on.

A photo of the thermo alarm


The archive includes full source code, along with gEDA source files for the schematic and a single-sided PCB layout.