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CHAPTER 14 SERIAL INTERFACE UART
The transmit/receive clock that is used to generate the baud rate is obtained by dividing the main system
clock.
• Use of main system clock to generate a transmit/receive clock for baud rate
The main system clock is divided to generate the transmit/receive clock. The baud rate generated by
the main system clock is determined according to the following formula.
f
X
[Baud rate] =
2
n+1
(k + 16)
f
: Main system clock oscillation frequency
X
n : Value set via TPS0 to TPS2 (1 ≤ n ≤ 8)
For details, see Table 14-2.
k : Value set via MDL0 to MDL3 (0 ≤ k ≤ 14)
Table 14-2 shows the relation between the 5-bit counter's source clock assigned to bits 4 to 6 (TPS0 to TPS2)
of BRGC and the "n" value in the above formula.
Table 14-2. Relation between 5-bit Counter's Source Clock and "n" Value
TPS2
TPS1
0
0
0
0
0
1
0
1
1
0
1
0
1
1
1
1
Remark f
: Main system clock oscillation frequency (f
X
[Hz]
TPS0
5-bit Counter's Source Clock Selection
0
f
/2
X
2
1
f
/2
X
3
0
f
/2
X
4
1
f
/2
X
5
0
f
/2
X
6
1
f
/2
X
7
0
f
/2
X
8
1
f
/2
X
= 8.38 MHz)
X
n
1
2
3
4
5
6
7
8
175
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