•Serial Communication
Modes 2 and 3 allow one "Master"
8051 to control several “Slaves” 8051.
•The serial port can be
programmed to generate an interrupt
(RI) if the 9th data bit = 1 by setting the SM2 bit in SCON.
•The TXD outputs of the
slaves are tied together and to the RXD input
of the master. The RXD inputs of the slaves are
tied together and to the TXD output of the master.
•Each slave is assigned
an address. Address bytes transmitted
by the master have the 9th bit = 1 & data bytes have it = 0.