Usart Baud Rates - Fujitsu MB96300 series Hardware Manual

MB96300 Super Series Hardware Manual
20.6

USART Baud Rates

One of the following can be selected for the USART serial clock source:
• Dedicated baud rate generator (Reload Counter)
• External clock as it is (clock input to the SCKn pin)
• External clock connected to the baud rate generator (Reload Counter)
■ USART baud rate selection
The baud rate selection circuit is designed as shown below. One of the following three types of baud rates
can be selected:
●
Baud rates determined using the dedicated baud rate generator (reload counter)
USART has two independent internal reload counters for transmission and reception serial clock. The baud
rate can be selected via the 16-bit reload value determined by the Baud Rate Generator Registers (BGRn).
The reload counter divides the peripheral clock CLKP1 by the value set in the Baud Rate Generator
Registers.
●
Baud rates determined using external clock (one-to-one mode)
The clock input from USART clock pulse input pins (SCK) is used as it is (synchronous). Any baud rate less
than the peripheral clock CLKP1 divided by 4 and is divisible can be set externally.
●
Baud rates determined using the dedicated baud rate generator with external clock
An external clock source can also be connected internally to the reload counter. In this mode it is used instead
of the internal peripheral clock CLKP1. This was designed to use quartz oscillators with special frequencies
and having the possibility to divide them.
CHAPTER 20 USART
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