yea what i got from a reference that the uc works on ttl vorltage 5 v and the Rs232 works on 3 volt so the max232 is used to make this convergence
isnt that right ?!
If it is hardware it can be built in to the microcontroller, or it can be an external chip.
If it is software, it is code that runs on the microcontroller, aka bit-bang code.
The UART logic level is that used by the processor, most often 0V and 5V. At least 3 wires are needed at each UART. RX, TX and a GND. This is all that is needed with no flow control or software flow control
To get the signal to travel further then possible with 0V and 5V you can use an RS232 level shifter. It converts the 0V/5V to +12V/-12V.
I don't like to complicate matters but this isn't strictly true, with micro-controllers, and a software UART, you can do it with just ground and a single I/O pin, a combined tx/rx - switched between tx and rx in the software. Obviously, unless you're short of pins, it makes more sense to use seperate ones - but it's perfectly capable with just the one I/O pin if needed.
I don't like to complicate matters but this isn't strictly true, with micro-controllers, and a software UART, you can do it with just ground and a single I/O pin, a combined tx/rx - switched between tx and rx in the software. Obviously, unless you're short of pins, it makes more sense to use seperate ones - but it's perfectly capable with just the one I/O pin if needed.
There are many ways to to what you want to do. What I was attempting to do was to keep it straight forward so you could get where you were going with the least difficulty.
Many of us here have years of experiance and could provide you with many ways doing this. That would be confusing to most anyone attemping to get his/her head around the basics.