We used Pulse-Width Modulation (PWM) to control an elevator. By using the PWM signals we controlled the elevator’s vertical position as well as open the door at each floor. Simultaneously we used the GPIO module to detect which floor the elevator is at.
We built the Morse Code decoder using polling and interrupts on an input switch. Output of the results are shown on LEDs (7 segments display) connected to output pins, and wrote diagnostic information to the serial port.
Dual-tone multi-frequency signaling (DTMF) is used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone handsets and other communications devices and the switching center. The version of DTMF used for push-button telephone tone dialing is known as Touch-Tone, first used by AT&T back in 1960s. DTMF is still used for a variety of purposes today. You may notice that while watching cable television there is sometimes an odd tone before local commercials. This tone is a DTMF signal telling the station to insert a local advertisement or station identification, and explains why these commercials that seem so out of place wind up on your television.
In this demo we generated various DTMF signal by taking inputs from the key pad.
