FUJITSU Semiconductor Controller MB89950/950A - Manual (Page 222)

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CHAPTER 10 UART
Table 10.4-2 Serial rate control register (SRC) bits
Bit Function
Bit 7
Bit 6 Unused bits • The read value is indeterminate.
• Writing to these bits has no effect on the operation.
Bit 5 CR:
Clock rate selection
bit • Used to select the asynchronous transfer clock rate. However, when the CS1 and
CS0 bit are "11
B
", the 1/8 clock rate is selected in spite of the value of the CR bit.
Bit 4
Bit 3 CS1, CS0:
Transfer clock
selection bits • Used to select the clock input of the UART. If the external or internal clock is
selected as clock input, the baud rate is a 1/16 or 1/64 clock frequency according to
the value of the CR bit.
Bit 2
Bit 1
Bit 0 RC2, RC1, RC0:
Baud rate
selection bits • Used to select the dedicated baud rate for the serial clock. One of eight baud rates
can be selected from different combination of these bits.