MICROCONTROLLER BASED TELECOM SWITCH. SPONSORED BY: ARJ ASIA External Guide: Mr. Jitendra Date Internal Guide: Mr. M.B. Tirmare By: Neha Purandare Janhavi Shah Sonali Shelke. PROBLEM:
SPONSORED BY: ARJ ASIA
External Guide: Mr. Jitendra Date
Internal Guide: Mr. M.B. Tirmare
By: Neha Purandare
A "telephone solicitation" is a telephone call that acts as an advertisement. Even if you have an unlisted, non-listed, or non-published telephone number, you may still receive unsolicited telephone calls with automated or prerecorded messages. In some cases unlisted or non-listed numbers can be obtained from a directory assistance operator. They, along with non-published numbers, may be sold to other organizations or people with whom you have done business. Some sales organizations call all numbers in numerical order for a neighborhood or area.
In the field of telecommunications, a telephone exchange (US: telephone switch) is a piece of equipment that connects phone calls. It is what makes your phone calls "work" in the sense of making connections and relaying the speech information. Here we are using our telecom switch to connect only the right call and block the unwanted ones.
The DTMF encoder resembles the telephone set. It uses DTMF encoder integrated circuit, Chip UM 91214B . This IC produces DTMF signals.
It consists of MT8870D chip which is a direct DTMF detector. Its output is a 4- bit BCD code; each 4 bit code corresponding to a DTMF tone pair. Whenever a valid tone pair is detected at the input, the StD pin goes high indicating that the tone pair has been latched.
PIC18F452 accepts the 4 bit BCD code from MT8870D and checks if the DTMF tone pair stands for numbers between 0 to 9. If it does, it is considered a valid no. and the user is allowed to receive the call; else it is routed to voice chip and rejected.
ISD2560 Voice chip:
If the call is unsolicited one, the P/R bar pin of this chip is pulled to Vcc and a message rejecting the call is played back to the caller. The message is pre-recorded on the chip by manual switching of P/R bar and CE bar pins.
• Linear program memory addressing to 32 Kbytes
• Linear data memory addressing to 1.5 Kbytes
ACCEPT INPUT TONES FROM MT8870D
IS TONE BET 0 TO 9?
MAKE RD0 = 1
MAKE RD1 = 1
The MPLAB C18 Code Development Systems are complete ANSI ‘C’ compilers for Microchip’s PIC18CXXX family of microcontrollers. This compiler provide powerful integration capabilities and ease of use not found with other compilers.
The PICSTART Plus development programmer is an easy-to-use, low cost, prototype programmer. It connects to the PC via a COM (RS-232) port. MPLAB
Integrated Development Environment software makes using the programmer simple and efficient. The PICSTART Plus development programmer supports all PICmicro devices with up to 40 pins.