TMP91C824
91C824-125
•
Integer divider (N divider)
For example, when the source clock frequency (fc) = 12.288 MHz, the input clock frequency =
φ
T2 (fc/16), the frequency divider N (BR0CR<BR0S3 to BR0S0>) = 5, and BR0CR<BR0ADDE>
= 0, the baud rate in UART Mode is as follows:
∗
Clock state
System clock: High frequency (fc)
Clock gear: 1 (fc)
Prescaler clock: System clock
Baud Rate =
÷
16
=
12.288
×
10
6
÷
16
÷
5
÷
16 = 9600 (bps)
Note: The N + (16 – K) / 16 division function is disabled and setting BR0ADD<BR0K3 to BR0K0>
is invalid.
•
N+(16-K)/16 divider (UART Mode only)
Accordingly, when the source clock frequency (fc) = 4.8 MHz, the input clock frequency =
φ
T0 ,
the frequency divider N (BR0CR<BR0S3 to BR0S0>) = 7, K (BR0ADD<BR0K3 to BR0K0>) = 3,
and BR0CR <BR0ADDE> = 1, the baud rate in UART Mode is as follows:
∗
Clock state
System clock: High frequency (fc)
Clock gear: 1 (fc)
Prescaler clock: System clock
Baud Rate =
÷
16
=
4.8
×
10
6
÷
4
÷
(7
+
13/16)
÷
16 = 9600 (bps)
Table 3.9.3, Table 3.9.4 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)> = fc / 4
•
In I/O Interface Mode
Baud rate = external clock input frequency
It is necessary to satisfy (external clock input cycle) >=16 / fc
fc/16
5
fc/4
7 + (16 – 3)/16