The RS232 serial port to TTL converter module is a board with the MAX3232 transceiver Integrated Circuit, which facilitates serial communication between TTL and RS232 ports by providing the necessary electrical signal conversion. These boards usually have a DB9 connector soldered at one end, and four header pins with jumper cables at the other end. The jumper cables enable the user to connect the wires to a breadboard or a microcontroller project board, whilst the DB9 connects directly to a COM port of a computer.
The MAX3232CSE IC, which comes in a 16 pin narrow SO package. It requires between 3.0 V to 5.5 V to operate, and has two receivers and two transmitters. It has a maximum guaranteed data rate of 120 kbps, and the circuitry requires four 0.1uF charge-pump support capacitors. It is also pin compatible with the famous MAX232 IC.
These boards connect to systems with a UART. hence, they work with ATMEL and PIC microcontrollers.