Книга: Introduction to Microprocessors and Microcontrollers

His and hers garage door opener

Here is a little task that a simple microprocessor can solve for us. When the woman arrives in her car, a light signal is flashed at the sensor and only her garage door opens. When the man arrives home, his car flashes a light signal at the same sensor but this time his garage door opens but hers remains closed.

The cars are sending a different sequence of light flashes to the light sensor. The light sensor converts the incoming light to electrical voltage pulses that are recognized by the microprocessor. The output voltage now operates the electrical motor attached to the appropriate door. The overall scheme is shown in Figure 1.5.

Figure 1.5 Opening the right garage door

In the unlikely event of it being needed, a modern microprocessor would find it an easy task to increase the number of cars and garages to include every car and every garage that has ever been manufactured. Connecting all the wires, however, would be an altogether different problem!

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