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•
Integer divider (N divider)
For example, when the source clock frequency (fc) = 12.288 MHz, the input clock
frequency = φT2 (fc/16), the frequency divider N (BR0CR<BR0S3:0>) = 5, and
BR0CR<BR0ADDE> = 0, the baud rate in UART mode is as follows:
* Clock state
fc/16
Baud rate =
= 12.288 × 10
Note: The N + (16 − K)/16 division function is disabled and setting
BR0ADD<BR0K3:0> is invalid.
•
N + (16 − K)/16 divider (UART mode only)
Accordingly, when the source clock frequency (fc) = 4.8 MHz, the input clock
frequency
=
φT0,
the
(BR0ADD<BR0K3:0>) = 3, and BR0CR <BR0ADDE> = 1, the baud rate in UART
mode is as follows:
* Clock state
Baud rate =
7 + (16 – 3)/16
= 4.8 × 10
Table 3.9.3 show examples of UART mode transfer rates.
Additionally, the external clock input is available in the serial clock (Serial
channels 0, 1). The method for calculating the baud rate is explained below:
•
In UART mode
Baud rate = External clock input frequency ÷ 16
It is necessary to satisfy (External clock input cycle) ≥ 4/fc
•
In I/O interface mode
Baud rate = External clock input frequency
It is necessary to satisfy (External clock input cycle) ≥ 16/fc
System clock:
Clock gear:
Prescaler clock: System clock
÷ 16
5
÷ 16 ÷ 5 ÷ 16 = 9600 (bps)
6
frequency
divider
N
System clock:
Clock gear:
Prescaler clock: System clock
fc/4
÷ 16
÷ 4 ÷ (7 + 13/16) ÷ 16 = 9600 (bps)
6
91C824-127
TMP91C824
High frequency (fc)
1 (fc)
(BR0CR<BR0S3:0>)
=
High frequency (fc)
1 (fc)
2008-02-20
7,
K
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