The Usart Bla bla bla
A little disquisition about USART and AVR microcontroller
The scope of this serie of articles is to explain the USART in depth and its use with the microcontroller AVR.
A new article will be published each week.
We assume you have a working knowledge of the C programming language and time to follow us 
History
All electronic devices, computers and micro controllers need to exchange data with other devices. One of the most used way, since 1969, is the serial transmission using the RS232 standard when the EIA defined it. Serial transmission is commonly used with modems and for non-networked communication between computers, terminals, printers and other devices It is useful for debugging purpose in embedded system. In the following paragraphs we describe the serial transmission in the two forms: Synchronous and Asynchronous.
The base of the serial transmission is the Universal [Synchronous] Asynchronous Receiver/Transmitter (U[S]ART) controller.
The U[S]ART transmits (the sender side) words of data sending individual bits in sequential way while on the other side (the destination side) a second U[S]ART re-assembles the bits into complete data words; even if the serial is not fast as the parallel transfer, it only requires two or three line and it gives the possibilities to send data to receiver that are not near the sender (up to 15 meters).
(to be continued…)