UART

Asynchronous serial: start bit, data bits, optional parity and stop bits at an agreed baud rate.

Easy

UART needs no shared clock — both sides agree on a baud rate (9600, 115200…). Idle is high; each frame is:

idle ─┐ start │ D0 D1 D2 D3 D4 D5 D6 D7 │ (parity) │ stop ┌─ idle
      └───────┘                                          └────

"8N1" means 8 data bits, no parity, 1 stop bit — 10 bits per byte, so 115200 baud carries 11 520 bytes/s.

Connect TX → RX and RX → TX, plus common ground. Clock mismatch beyond about 2–3 % causes errors. Logic-level UART is not RS-232 (which uses ±3 to ±15 V) — use a converter like the MAX232.

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