There are serveral rs232 transceiver circuit which commond used for communicated between microcontroller and other devices such PC or any devices that use rs232.Here is a collection of rs232 transceiver circuits that popular for today.
2 transistor The circit below use 2 transistor and some components to provide RS232 transceiver.It usefull for cheap application that dose not long lenght.
MAX232(Full duplex) The circuit below use MAX232 which is the MAXIM's devices.This circuit is very stable and use for professional design. This device is inexpensive and it can provides 2 channel for RS232 . The MAX232 line drivers/receivers are designed for RS-232 and V.28 communications in harsh environments. Each transmitter output and receiver input is protected against ?15kV electrostatic discharge (ESD) shocks, without latchup.It can operate from a Single +5V Power Supply.
DS275(Half Duplex) This RS232 transceiver circuit use DS275 which is a small half duplex transceiver chip.I Compatible with RS–232–E signals and suitible for Low–power serial transmitter/receiver for battery-backed application.Requies no external devices.