AT89C5122 ATMEL [ATMEL Corporation], AT89C5122 Datasheet - Page 134

• Manufacturer Part Number: AT89C5122
• Description: MICROCONTROLLER WITH USB AND SMART CARD READER INTERFACES
• Manufacturer: ATMEL [ATMEL Corporation]

Table 76. Internal Baud Rate Generator Value
Baud Rate Selection (Mode 2)
134
Baud Rate
Baud Rate
115200
115200
57600
38400
19200
57600
38400
19200
9600
4800
9600
4800
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
230
204
249
243
236
217
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 81 the selection is done using SMOD1 bit in PCON register.
Figure 82 gives the baud rate calculation formula depending on the selection.
Figure 81. Baud Rate Generator Selection (Mode 2)
Figure 82. 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
⋅
/ 2
F
SMOD1
SMOD1
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
0
1
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
³ 16
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
251
246
240
225
194
131
243
230
217
178
100
N/A
4202D–SCR–06/05
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