Serial Port Complete - Latest Microcontroller projects

Formats and Protocols

For receivers that require a little extra time to accept received data, some UARTs

enable the transmitter to stretch the Stop bit to the width of 1.5 or 2 bits. The

original purpose of the longer Stop bit was to allow time for mechanical tele-

type machines to settle to an idle state.

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The bit rate is the number of bits per second transmitted or received per unit of

time, usually expressed as bits per second (bps). Baud rate is the number of pos-

sible events, or data transitions, per second. In the basic, wired, digital transmis-

Figure 2-1: Synchronous transmissions include a clock line, while asynchronous

transmissions require each computer to have its own clock.