Serial Communications (16C452)
Baud Rate Generator
The serial baud rate generator takes the clock input (1.8432 MHz) and
divides it by any divisor from 1 to 65,536. The output frequency of
the baud generator is 16 times the baud rate.
Two 8-bit latches store the divisor in a 16-bit binary format. These
divisor latches must be loaded during initialization in order to ensure
desired operation of the baud rate generator.
When loading either of the divisor latches, a 16-bit baud counter
immediately becomes effective. Table 8-4 illustrates the use of the
baud generator with the on-board 1.8432 MHz oscillator.
The baud rate divisor was calculated from the following relationship:
D = F/(16 x B)
where: D is the divisor value
F is the clock frequency (1.8432 MHz), and
B is the baud rate.
Note: The maximum operating frequency of the baud generator is
1.8432 MHz. However, when using divisors of 5 and below, the
maximum frequency is equal to the divisor in MHz (a "1" divisor =
1 MHz maximum frequency). In no case should the data rate be
greater than 56 Kbaud.
8-24
