Uart0 Baud Rate - Fujitsu MB90895 Series Hardware Manual

14.5

UART0 baud rate

The UART0 transmission/reception clock is selected from among the following options:
• Dedicated baud rate generator
• Internal clock (16-bit reload timer output)
• External clock (clock input to SCK pin)
I Select of UART0 Baud Rate
The UART0 baud rate select circuit comprises as shown in Figure 14.5-1.The clock input source can be
selected from among the following three types:
G
Baud rate by dedicated baud rate generator
• To use the dedicated baud rate generator incorporated in the UART0 as a clock input source, set the CS2
to CS0 bits in the serial mode register to "000
rate can be selected from six types.
G
Baud rate by internal timer
• To use the internal clock signal supplied from 16-bit reload timer 0 as the clock input, set the CS2 to
CS0 bits in the serial mode register to "110
• The baud rate is the value resulting from dividing the frequency of the clock signal supplied from 16-bit
reload timer 0 by 2 in the clock synchronous mode or the value resulting from dividing the frequency of
the supplied clock signal by 32 in the clock asynchronous mode.
• Any baud rate can be selected according to the setting values of the 16-bit reload timer.
G
Baud rate by external clock
• To use the external clock signal input via the clock input pin (SCK0) of the UART0 as the clock input,
set the CS2 to CS0 bits in the serial mode register to "111
• The baud rate is the value equal to the frequency of the external clock signal supplied in the clock
synchronous mode or the value resulting from dividing the frequency of the input clock signal by 16 in
the clock asynchronous mode.
• Any baud rate can be used if the external clock frequency is 2 MHz or less.
" to "100 " depending on the baud rate used.The baud
B B
".
B
".
B
CHAPTER 14 UART0
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