Figure 18-5. Reception Waveforms (Mode 0)
TXD
Set REN, Clear RI
Write to SCON
RXD
RI
D0
D1
D2
D3
D4
D5
D6
D7
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)
PER
CLOCK
÷ 6
0
To Serial Port
1
IBRG0
CLOCK
M0SRC
BDRCON.0
Figure 18-7. Baud Rate Formulas (Mode 0)
FPER
16 (256 -BRL)
Baud_Rate=
6(1-SPD)
⋅
⋅
FPER
Baud_Rate
=
FPER
16 Baud_Rate
6
BRL= 256 -
6(1-SPD)
⋅
⋅
a. Fixed Formula
b. Variable Formula
110
AT89C5132
4173E–USB–09/07
ATMEL [ ATMEL ]
