
110
4173E–USB–09/07
AT89C5132
Figure 18-5. Reception Waveforms (Mode 0)
18.3.3
Baud Rate Selection
(Mode 0)
In mode 0, the baud rate can be either fixed or variable.
As shown in
Figure 18-6, the selection is done using M0SRC bit in BDRCON register.
Figure 18-7 gives the baud rate calculation formulas for each baud rate source.
Figure 18-6. Baud Rate Source Selection (mode 0)
Figure 18-7. Baud Rate Formulas (Mode 0)
Write to SCON
TXD
RXD
RI
D0
D1
D2
D3
D4
D5
D6
D7
Set REN, Clear RI
0
1
M0SRC
BDRCON.0
PER
CLOCK
÷
6
To
IBRG0
CLOCK
Serial Port
Baud_Rate=
6(1-SPD)
16 (256 -BRL)
F
PER
BRL= 256 -
6(1-SPD)
16 Baud_Rate
F
PER
a. Fixed Formula
b. Variable Formula
Baud_Rate=
6
FPER