Communication Protocols
UART is the agreement between two people talking without a shared clock wire: they say "we will both speak at 9600 bits per second" and trust their separate watches. When idle, the line rests at 1 — silence is the high level.
The conversation happens in frames (see the diagram): first the line is pulled to 0 (start — "listen, here I go!"), then 8 data bits follow least-significant bit first, and a stop bit (1) gives a breath. In the 8N1 format one character costs 10 bits.
The receiver’s trick is timing: it catches the start edge, then samples right in the middle of each bit — staying clear of the uncertainty at the edges. At 9600 baud one bit lasts 104 µs; this is exactly what the Logic Analyzer does.
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