•Two SFRs (SBUF & SCON) provide software access to serial port.
–Writing to SBUF loads data to be
transmitted and reading SBUF accesses received data.
–SCON is a bit addressable register
containing status bits and control bits. Control bits set the operating mode and status
bits indicate the end of a character transmission or reception. The status
bits are tested in software or programmed to cause an interrupt.
•Serial port frequency of operation (baud rate) can be
fixed or variable.
–Fixed is derived from on-chip
oscillator and variable is supplied by Timer 1 which must be programmed accordingly.