in the quiz question 1, it asked how many physical connection is needed.

by that, is it asking for

a) the port? i.e. 1 usb connection
or
b) the amount of wires needed? which i think is 2, 1 for tx and one for rx.

thanks in advance!
— zhikai

[Jason] If you refer to my slide on full-duplex serial data transfer, you will see there are three wires. Tx, Rx and Gnd. Ground wire is needed to ensure the ground reference for both Tx and Rx is the same, so that 5V on the transmitting system is also seen as 5V on the receiving end.