Datasheet

110
AT89C5132
4173C–USB–07/04
Notes: 1. These frequencies are achieved in X1 mode, F
PER
= F
OSC
÷ 2.
2. These frequencies are achieved in X2 mode, F
PER
= F
OSC
.
Baud Rate Selection (Mode 2) In mode 2, the baud rate can only be programmed to two fixed values: 1/16 or 1/32 of
the peripheral clock frequency.
As shown in Figure 88 the selection is done using SMOD1 bit in PCON register.
Figure 89 gives the baud rate calculation formula depending on the selection.
Figure 88. Baud Rate Generator Selection (mode 2)
Figure 89. Baud Rate Formula (Mode 2)
Table 90. Baud Rate Generator Configuration
Baud Rate
F
PER
= 6 MHz
(1)
F
PER
= 8 MHz
(1)
F
PER
= 10 MHz
(1)
SPD SMOD1 BRL Error% SPD SMOD1 BRL Error% SPD SMOD1 BRL Error%
115200 - -----------
57600 - - - - 1 1 247 3.55 1 1 245 1.36
38400 1 1 246 2.34 1 1 243 0.16 1 1 240 1.73
19200 1 1 236 2.34 1 1 230 0.16 1 1 223 1.36
9600 1 1 217 0.16 1 1 204 0.16 1 1 191 0.16
4800 1 1 178 0.16 1 1 152 0.16 1 1 126 0.16
Baud Rate
F
PER
= 12 MHz
(2)
F
PER
= 16 MHz
(2)
F
PER
= 20 MHz
(2)
SPD SMOD1 BRL Error% SPD SMOD1 BRL Error% SPD SMOD1 BRL Error%
115200 - - - - 1 1 247 3.55 1 1 245 1.36
57600 1 1 243 0.16 1 1 239 2.12 1 1 234 1.36
38400 1 1 236 2.34 1 1 230 0.16 1 1 223 1.36
19200 1 1 217 0.16 1 1 204 0.16 1 1 191 0.16
9600 1 1 178 0.16 1 1 152 0.16 1 1 126 0.16
4800 1 1 100 0.16 1 1 48 0.16 1 0 126 0.16
0
1
SMOD1
PCON.7
PER
CLOCK
÷ 2
÷ 16
To Serial Port
Baud_Rate =
32
2
SMOD1
⋅ F
PER