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RS-232

RS-232 is nowadays a 'mature' communication standard. It is surprising that a standard, defined in the early sixties, is still widely used today. Formally however, the name RS-232 does not apply to a standard. An American organisation, now known as the Electronic Industries Association, proposed a way to communicate between large mainframe computers and peripheral equipment such as terminals. The proposal was called a Recommended Standard and 232 was not more than a identifying number. Much later this became an official standard, EIA-232. In 1991, the latest version, EIA-232E was published. However, the name RS-232 is still widely used and so shall I in these pages.
RS-232 is a serial communication protocol. It sends information as bit after bit and has two signal levels:

- a voltage between -3 and -25 Volts is a logic one (1)
- a voltage between +3 and +25 Volts is a logic zero (0

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Posted by waqasahmad

The MAX232 was the first IC which in one package contains the necessary drivers (two) and receivers (also two), to adapt the RS-232 signal voltage levels to TTL logic. It became popular, because it just needs one voltage (+5V) and generates the necessary RS-232 voltage levels (approx. -10V and +10V) internally.

The MAX232 is a chip that converts signals from your computers serial port to signals suitable for usage in our circuits. It uses electrolytic capacitors to store and pump up 5V to the +12 and -12V required by the RS232 serial communications protocol (that's what comes out of your PC or USB serial port adaptor).

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Posted by sagitraz