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embedded systems · serial communication

UART byte reception timing

A UART reception timing diagram shows how an asynchronous serial byte is framed on the receive line. The line is idle high, drops for the start bit, carries eight data bits and returns high for the stop bit. Sample points show where a receiver checks each bit, while the busy signal indicates the interval in which the receiver is handling the frame. This compact view helps firmware and hardware engineers confirm a protocol description, explain a logic-analyzer capture or document a test case. Add parity, a second stop bit, baud-rate timing or an error flag when the interface needs them. Keep every signal aligned to the same bit intervals so the framing is unambiguous.

Type Timing / waveform diagramStandard WaveDrom-compatible signal descriptionEngine schematex-timingUpdated 9/24/2026
UART byte reception
Drawing preview
The request

“Draw a UART byte reception timing diagram with an idle-high RX line, one start bit, data bits 0, 1, 0, 1, 0, 1, 0, 1, one stop bit, sample points, receiver busy, frame OK, and data-valid signals.”

Then tryChange the data byte to 0xA5.Add an active-low reset signal.
What is in this drawing

Read the decisions behind it.

01Frame boundaries

Show idle high, a start bit and a stop bit around the data.

02Sampling

Include sample points so the receiver timing is visible.

03Receiver status

Mark the busy interval over the active frame.

Use for a basic asynchronous UART frame when bit timing is the main point of the drawing.

More like this

Other examples in this family.

Browse all timing diagram templates →

FAQ

Common questions

What is a UART start bit?

It is the low bit that marks the beginning of an asynchronous serial frame after the line has been idle high.

How many data bits are shown?

This example shows eight data bits, a common UART configuration.

Why show sample points?

They make the receiver's timing reference clear when reviewing firmware or hardware behavior.