Does UART require a pullup resistor?
December 1, 2009
I am trying to understand how UART communication works.
I have not read anything stating that pullup resistors are required for UART, but conceptually some type of pullup is in fact required because otherwise there would be an unknown state.
Is it part of the UART standard that each device on the bus must have it's own pull-up resistor? If so how can this be because if the pull-ups are of different voltage then the state is again unknown.