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19.5
Baud Rate
When the dedicated baud rate generator is used, the following two types of baud rates
are available:
• CLK synchronous baud rate
• CLK asynchronous baud rate
■ CLK Synchronous Baud Rate
The five URD register bits: BCH, BCH0 and RC3, RC2, RC1 select the baud rate for CLK synchronous
transfer.
First select the machine clock divider ratio using BCH and BCH0.
BCH BCH0
0
0
1
1
Then, set the division ratio for the clock selected above in RC3, RC2, RC1, and RC0. The following three
settings are available for CLK synchronous transfer. Other settings are prohibited.
RC3 RC2 RC1 RC0
0
0
1
0
-->
Divide by 6 [For example, at 24 MHz: 24/6 = 4 MHz]
1
-->
Divide by 4 [For example, at 16 MHz: 16/4 = 4 MHz]
0
-->
Divide by 3 [For example, at 12 MHz: 12/3 = 4 MHz]
1
-->
Divide by 5 [For example, at 20 MHz: 20/5 = 4 MHz]
1
0
1 -->
Divide by 2 [For example, at 4 MHz: 4/2 = 2.0 Mbps]
1
1
1 -->
Divide by 4 [For example, at 4 MHz: 4/4 = 1.0 Mbps]
0
0
1 -->
Divide by 8 [For example, at 4 MHz: 4/8 = 0.5 Mbps]
(At 2 MHz, the speed becomes half the above examples.)
CHAPTER 19 UART0, UART1
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