BAUD RATE SELECTION
The 16450 or 16550 UART determines the baud rate of the serial output using a combination of the clock input frequency and the value written to the divisor latches. Standard personal computer serial interfaces use an input clock of 1.8432 MHz. A table of baud rates available is given in Figure 22.
DESIRED BAUD | DIVISOR LATCH | ERROR BETWEEN DESIRED AND ACTUAL |
RATE | VALUE | VALUES (%) |
|
|
|
50 | 2304 | - |
|
|
|
75 | 1536 | - |
|
|
|
110 | 1047 | 0.026 |
|
|
|
150 | 768 | - |
|
|
|
300 | 384 | - |
|
|
|
600 | 192 | - |
|
|
|
1200 | 96 | - |
|
|
|
1800 | 64 | - |
|
|
|
2000 | 58 | 0.69 |
|
|
|
2400 | 48 | - |
|
|
|
3600 | 32 | - |
|
|
|
4800 | 24 | - |
|
|
|
7200 | 16 | - |
|
|
|
9600 | 12 | - |
|
|
|
19200 | 6 | - |
|
|
|
38400 | 3 | - |
|
|
|
56000 | 2 | 2.86 |
|
|
|
Figure 22 --- Divisor Latch settings for common baud rates
using 1.8432 MHz input clock
Quatech | 23 |
