is ttl the same as uart?
UART = Universal Asynchronous Receiver/Transmitter. It is the basic chip (or virtual function in a microcontroller) which encodes the data bits serially into a standard format with a start bit, stop bit(s), speed, etc. ... A TTL UART will output (and input) only TTL levels, essentially 0 bit = 0V and 1 bit = 5V.