Question

Does the UART Architecture require an external clock?

(a) Yes

(b) No

This question was posed to me in examination.

Origin of the question is Serial and Stream Communications in section Arduino Programming of Arduino

Answer 1

Correct answer is (b) No

To elaborate: UART stands for Universal Asynchronous Receiver/Transmitter. This means all communication here is not governed by the presence of a clock unlike the I2C and the SPI protocol which require an extra pin for performing serial communications.