hi all,
i am uploading here project entitled "Fuel Price Highway Billboard".
The project is a highway billboard that displays the fuel prices for a gas station using 7-segment displays. A telephone line is connected to the billboard and the 7-segment displays can be controlled by the keypad of a touchtone telephone. The circuit contains a ring detector to determine when the phone line is ringing and then answers the line by completing the phone line circuit. A DTMF decoder is used to convert the DTMF signal from the touchtone telephone into a 4-bit binary output. A PIC™ microcontroller is used to accept the 4-bit binary output of the DTMF decoder for verifying a three-digit password and to display the fuel prices using the 7-segment displays
regards
john