Uart Baud Rate - Fujitsu MB90335 Series Hardware Manual

CHAPTER 18 UART

18.6 UART Baud Rate

18.6 UART Baud Rate
The sending and receiving clocks of UART has the following alternatives.
• Internal clock (reload counter)
• External clock (reload counter)
• External clock (clock input to SCK pin)
■ UART Baud Rate Selection
You can select one of the following three different baud rates:
●
Baud rate resulting from a dedicated baud rate generator of the internal clock.
The baud rate can be selected by setting the 11-bit reload value on settings of the UART prescaler control
registers 0, 1 (UTCR0, UTCR1), and the UART prescaler reload registers 0, 1 (UTRLR0, UTRLR1). The
reload counter divides the machine clock by the specified value. It is used in the synchronous and
asynchronous modes.
●
Baud rate resulting from a dedicated baud rate generator of the external clock.
The external clock is used as the clock source for the reload counter. The baud rate can be selected by
setting the 11-bit reload value on settings of the UART prescaler control registers 0, 1 (UTCR0, UTCR1),
and the UART prescaler reload registers 0, 1 (UTRLR0, UTRLR1). The reload counter divides the external
clock frequency by the set value. It is used in the asynchronous modes.
●
Baud rate of the external clock (one-to-one mode)
The clock that is entered from the UART clock input pins (SCK0, SCK1) is used as the baud rate as it is. It
is used in the synchronous mode.
410 FUJITSU MICROELECTRONICS LIMITED
MB90335 Series
CM44-10137-6E