Embedded Project on Display of Dialed Telephone Numbers on Seven Segment Displays


The main goal of this project is to display dialed telephone numbers on an arrangement of seven-segment LED-based display framework for better visibility by utilizing the idea of DTMF (double tone multi recurrence) sensing.

Each button on the keypad of the telephone produces a unique frequency when pressed. These frequencies are decoded by a DTMF decoder and digital signals from its output are fed to a microcontroller through buffer circuits. While the program is executed, the output of the microcontroller delivers the same information to parallel associated seven-segment displays.

The parallel associated seven-segment display operates in multiplexing mode fed from the microcontroller through driving transistor switches to produce the correct display of the dialed numbers. In a parallel associated a few 7 segment units, one seven-segment display demonstrates the number at any given time out of the ten utilized. Attributable to a persistence of vision, every one of the numbers same glowing in the meantime as they are in high-speed multiplexing mode.

The project utilizes a 8051 family microcontroller, and a PDA/or landline properly associated from its earphone socket to the DTMF decoder for receiving information. This information is transmitted to the microcontroller for processing. This processed information is then given to the parallel associated seven-segment display.

Moreover, this project can be improved by displaying time, cost, and date parameters on a digital display.

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