AT83C5122_08 ATMEL [ATMEL Corporation], AT83C5122_08 Datasheet - Page 132

• Manufacturer Part Number: AT83C5122_08
• Description: C51 Microcontroller with USB and Smart Card Reader Interfaces
• Manufacturer: ATMEL [ATMEL Corporation]

Table 76. Internal Baud Rate Generator Value
Baud Rate Selection (Mode 2)
132
Baud Rate
Baud Rate
115200
115200
57600
38400
19200
57600
38400
19200
9600
4800
9600
4800
AT83R5122, AT8xC5122/23
SPD
SPD
1
1
1
1
1
1
1
1
1
1
1
1
SMOD1
SMOD1
F
F
CK_IDLE
CK_IDLE
1
1
1
1
1
1
1
1
1
1
1
1
= 12 MHz
= 4 MHz
BRL
BRL
254
252
249
243
249
243
236
217
230
204
178
100
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 80 the selection is done using SMOD1 bit in PCON register.
Figure 81 gives the baud rate calculation formula depending on the selection.
Figure 80. Baud Rate Generator Selection (Mode 2)
Figure 81. Baud Rate Formula (Mode 2)
For mode 0 for UART, thanks to the bit M0SRC located in BDRCON register (Table 82)
Baud_Rate =
CK_
SI
Error%
Error%
8.51
8.51
6.99
0.16
0.16
0.16
6.99
0.16
2.34
0.16
0.16
0.16
SPD
SPD
2
SMOD1
1
1
1
1
1
1
1
1
1
1
1
1
32
x2
SMOD1
SMOD1
F
F
CK_SI
F
CK_IDLE
CK_IDLE
1
1
1
1
1
1
1
1
1
1
1
1
= 16 MHz
SMOD1
= 8 MHz
PCON.7
1
0
BRL
BRL
252
247
243
230
204
152
247
239
230
204
152
48
Error%
Error%
8.51
3.55
0.16
0.16
0.16
0.16
3.55
2.12
0.16
0.16
0.16
0.16
/32
SPD
SPD
1
1
1
1
1
1
1
1
1
1
1
1
To Serial Port
SMOD1
SMOD1
F
F
CK_IDLE
CK_IDLE
1
1
1
1
1
1
1
1
1
1
1
1
= 9.6 MHz
= 24 MHz
BRL
BRL
4202F–SCR–07/2008
251
246
240
225
194
131
243
230
217
178
100
N/A
Error%
Error%
4.17
4.17
2.34
0.81
0.81
0.00
0.16
0.16
0.16
0.16
0.16
N/A