Baud Rate Selection; Table 5.3. Baud Rate And Divisors - Contec COM-2(PCI) User Manual

I/O Ports and Registers

Baud Rate Selection

The board contains a 16552 equivalent (16654 equivalent on the
COM-8(PCI)) controller IC with a software-selectable 3.6864MHz
clock input. The 16552 equivalent contains an internal baud rate
generator that allows the baud rate to be specified by software.
The ACE can divide the selected clock input (1.8432 or
3.6864MHz) by any value between 1 and (2
frequency of the baud rate generator is 16 times the specified baud
rate.
Two 8-bit division registers store the division ratio as a 16-bit
binary value. These division registers need to be set when
initializing to ensure reliable baud rate generator operation.
Note!
For selecting the clock signal (1.8423 or 3.6864 MHz), see the
"Interrupt Vector Register" section.

Table 5.3. Baud Rate and Divisors

115200
230400
54
Divisor = clock frequency / (Baud rate x 16)
Desired Clock = 1.8432MHz
baud rate Divisor
50 2304
75 1536
110 1047
134.5
857
150 768
300 384
600 192
1200 96
1800 64
2000 58
2400 48
3600 32
4800 24
7200 16
9600 12
14400 8
19200 6
28800 4
38400 3
57600 2
1
COM-2(PCI), COM-4(PCI), COM-8(PCI)
Clock = 3.6864MHz
Percent error Divisor
- 4608
- 3072
0.026 2094
0.058 1713
- 1536
- 768
- 384
- 192
- 128
0.68 115
- 96
- 64
- 48
- 32
- 24
- 16
- 12
- 8
- 6
- 4
- 2
1
16
-1). The output
Percent error
-
-
0.03
0.0005
-
-
-
-
-
0.17
-
-
-
-
-
-
-
-
-
-
-
-