CHAPTER 10 SERIAL INTERFACE FUNCTION
293
The baud rate transmit/receive clock that is generated is obtained by dividing the main clock.
•
Generation of baud rate transmit/receive clock using main clock
The transmit/receive clock is obtained by dividing the main clock. The following equation is used to obtain the
baud rate from the main clock.
<When 8
≤≤≤≤
k
≤≤≤≤
255>
[Baud rate] = [Hz]
f
xx
: Main clock oscillation frequency
m : Value set by TPSn2 to TPSn0 (0
≤
m
≤
5)
k
: Value set by MDLn7 to MDLn0 (8
≤
k
≤
255)
•
Baud rate tolerance
The baud rate tolerance depends on the number of bits in a frame and the counter division ratio [1/(16+k)].
Table 10-8 shows the relation between the main clock and the baud rate and Figure 10-33 shows an example
of the baud rate tolerance.
Table 10-8. Relation between Main Clock and Baud Rate
Baud Rate
fxx = 17 MHz
fxx = 10 MHz
fxx = 5 MHz
(bps)
k
m
Error (%)
k
m
Error (%)
k
m
Error (%)
1200
221
5
0.16
130
5
0.16
130
4
0.16
2400
221
4
0.16
130
4
0.16
130
3
0.16
4800
221
3
0.16
130
3
0.16
130
2
0.16
9600
221
2
0.16
130
2
0.16
130
1
0.16
19200
221
1
0.16
130
1
0.16
130
0
0.16
31250
136
1
0.00
160
0
0.00
80
0
0.00
38400
221
0
0.16
130
0
0.16
65
0
0.16
76800
111
0
−
0.29
65
0
0.16
33
0
−
1.36
150 K
55
0
0.62
33
0
−
1.36
16
0
1.73
300 K
28
0
−
1.18
16
0
1.73
8
0
1.73
Remark
fxx: Main clock oscillation frequency
f
xx
2
m+1
×
k
Содержание V850/SA1 mPD703015
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