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CHAPTER 19 UART
❍ Internal timer
The applicable baud rate when CS2 to CS0 are set to "110" and the internal timer (PPG1) is
selected can be calculated by the following expressions:
Asynchronous (start-stop synchronization): (φ / N) /(16 x 2 x (n + 1))
CLK synchronous: (φ / N)/(2 x (n + 1))
N: Count clock source of the timer (PPG1)
n: Reload value of the timer (PPG1)
Table 19.5-4 shows the relationship between the baud rate and reload value when the machine
clock frequency is 7.3728 MHz.
Table 19.5-4 Relationship between baud rate and reload value
Baud rate
38400
19200
9600
4800
2400
1200
600
300
- : Indicates that a setting is prohibited
Note:
Please do not use the following setting at the clock synchronization.
N = 1, n = 0
❍ External Clock
The baud rate when CS2 to CS0 are set to "111" can be calculated by the following
expressions:
Asynchronous (start-stop synchronization): f / 16
CLK synchronous: f'
f can be up to 1/2 of the machine clock. f' can be up to 1/8 of the machine clock.
426
(machine clock frequency: 7.3728 MHz)
Clock asynchronous
(Start-Stop synchronization)
1
N = 2
(divide-by-2 of
(divide-by-8 of
machine clock)
machine clock)
2
5
11
23
47
95
191
383
Reload value
Clock synchronous
3
N = 2
N = 2
(divide-by-2 of
machine clock)
-
47
-
95
2
191
5
383
11
767
23
1535
47
3071
95
6143
1
3
N = 2
(divide-by-8 of
machine clock)
11
23
47
95
191
383
767
1535
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