Microcontroller and system for controlling trial times in a furnace system.

摘要

A microcontroller controlling a fuel valve (35) allows for more than one trial time in a furnace system, while using only one pin of the microcontroller. An alternating current signal at an input port (20) of the microcontroller causes the microcontroller to allow a first long trial time period. Any direct current signal at the input port causes the microcontroller to allow only a second shorter trial time period. The trial time input port (20) of the microcontroller is placed between two other ports (15, 25) which either receive or send direct current signals. IMAGE