microcontroller based epabx system

[shamal]

epabx system and microcontroller

hi this shamal.
i am an engineering student .i am ding project ON MICROCONTROLLER BASED EPABX SYSTEM (2+8).can anybody guide me how to proceed.which controller IC should i use.plz help me

 

[artem]

epabx project

just few words .... try to write logic and implement timing diagram for project . it is all about capabilities and features . You have to define requirements :
a. Dialing type tone or pulse or both
b. Number of subscriber lines to implement
c. Conference call possibility
d. Tone provision to subscribers (ting back wait , busy ...)
e. Number of same time active calls (defines number of crosses in commutation matrix )
f. External PSTN line connection (interface types quantity)
g. User interface type to for configuration purposes
h. Other featuers not covered here , some kind of supplementary services to pabx suubscriber
.

Then study have to be done for possible solutions - write down necessary timing and memory requirements to accomplish project. Then multiply these results by some number dependent on feature expansion possibility and unexpected difficulties resulted in more computing power and memory consumption (you can use 1.5 -3 dependent on your experience as developer and extend of study) . Of course you will need to calculate number of interface lines and type of signalling to peripherials (such as dtmf tone decoders , analog switch multiplexros , ring controlm hook on control ....)

At the end you will have :
- processing capacity in terms of least access time needed
- peripherial interface types needed for microcontroller interfacing
- number of gpio or other interface types
- memory usage
- (let say power requirements , backup configuration eeprom need ....)

then you can come back and repeat your original question in terms of figures and numhers , so somebody will be able to provide expected by you kind of assistance .

P.S. Of course i could miss something to mention above .