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CHAPTER 15 UART1
15.5.2
Baud Rate by Internal Timer (16-bit Reload Timer)
The setting when selecting the internal clock supplied from the 16-bit reload timer 1 as
the clock input source of the UART1 and the baud rate calculation are shown below.
I Baud Rate by Internal Timer (16-bit Reload Timer Output)
The baud rate based on the internal timer (16-bit reload timer output) is set by setting the clock input source
select bits (SMR1 register bit 5 to 3: CS2 to CS0) to "110
division ratio of the count clock and the reload value of the 16-bit reload timer.
shows the baud rate selector based on the internal timer.
• If the internal timer (16-bit reload timer) is selected as a clock input source (SMR1 register bit 5 to 3: CS2
to CS0), the 16-bit reload timer output pin (TOT) is connected internally and does not need to be
connected externally to the external clock input pin (SCK).
• The 16-bit reload timer output pin (TOT) can be used as a general-purpose I/O port unless otherwise
used.
Figure 15.5-3 Baud Rate Selector by Internal Timer (16-bit Reload Timer Output)
16-bit reload timer output
(Specifying frequency by
count clock dividing ratio
and reload value)
G
Calculation expression for baud rate
Asynchronous baud rate =
Clock synchronous baud rate =
φ:Machine clock
N: division ratio based on communication prescaler for 16-bit reload timer (2
n: reload value for 16-bit reload timer (0 to 65,535)
458
SMR1: CS2 to CS0 = "110
(Clock input source select bit)
(Operating mode select bit)
16 2
/N
2
n 1
frequency
".Any baud rate can be set by selecting the
B
"
B
Clock selector
1/1 [Clock synchronous]
1/16 [Asynchronous]
SMR1: MD1, MD0
/N
bps
n 1
bps
Baud rate
1
3
5
, 2
, 2
)]
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