•8051 includes an on-chip serial port that can operate in
four modes over a wide range of frequencies.
•Essential function of serial port is to perform
parallel-to-serial conversion for output data,
and serial-to-parallel conversion for
•Transmission bit is P3.1 on pin 11 (TXD) and reception bit
is P3.0 on pin 10 (RXD).
•Features full duplex (simultaneous reception and transmission).
•Receive buffering allowing one character to be received and held in a buffer while a second character is
received. If the CPU reads the first
character before the second is fully received,
data are not lost.