•Baud rate is also affected by a bit in the PCON
register. PCON.7 is SMOD bit. If SMOD = 1,
baud rate will be doubled in modes 1, 2 and
3.
•Mode 2 baud rate is the 1/64th the oscillator
frequency (SMOD = 0) and can be doubled to
1/32nd the oscillator frequency
(SMOD = 1).
•PCON is not bit-addressable, setting SMOD without altering the other bits requires a “read-modify-write” operation as
follows:
• MOV A, PCON ; Get
current value of PCON
• SETB ACC.7 ; Set SMOD
• MOV PCON, A ; Write value back to PCON