Rainbow Electronics AT89C51SND1C - Manual (Page 139)

139
AT8xC51SND1C
4109E–8051–06/03
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 2 fixed values: 1/16 or 1/32 of the
peripheral clock frequency.
As shown in Figure 107 the selection is done using SMOD1 bit in PCON register.
Figure 108 gives the baud rate calculation formula depending on the selection.
Figure 107. Baud Rate Generator Selection (Mode 2)
Table 124. Internal Baud Rate Generator Value
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
ч 2
ч 16 To Serial Port