Serial Protocol
Serial Protocol is based on transmitting bytes, and receiving them. For this,
they have two wires - RX
and TX
. When connecting two devices (like arduino and
USB - UART TTL converter), they must be twisted. See
how to program arduino mini
for an example.
Main problems of this protocol, is that you can connect only two devices together, not more.
Other protocols like SPI
or I2C
handle this problem.