CHAPTER 10 SERIAL INTERFACE FUNCTION
User’s Manual U13850EJ4V0UM
324
(b) Baud rate
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 TPSn3 to TPSn0 (0
≤
m
≤
9)
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 10-9 shows the relationship between the main clock and the baud rate, and Figure 10-42 shows an
example of the baud rate tolerance.
Table 10-9. Relationship Between Main Clock and Baud Rate
f
XX
= 8 MHz
f
XX
= 12.58 MHz
f
XX
= 16 MHz
Note
f
XX
= 20 MHz
Note
Baud Rate
(bps)
k
m
Error (%)
k
m
Error (%)
k
m
Error (%)
k
m
Error (%)
32
244
9
0.06
–
–
–
–
–
–
–
–
–
64
244
8
0.06
192
9
–0.02
244
9
0.06
–
–
–
128
244
7
0.06
192
8
–0.02
244
8
0.06
152
9
0.39
300
208
6
0.16
164
7
–0.12
208
7
0.16
130
8
0.16
600
208
5
0.16
164
6
–0.12
208
6
0.16
130
7
0.16
1200
208
4
0.16
164
5
–0.12
208
5
0.16
130
6
0.16
2400
208
3
0.16
164
4
–0.12
208
4
0.16
130
5
0.16
4800
208
2
0.16
164
3
–0.12
208
3
0.16
130
4
0.16
9600
208
1
0.16
164
2
–0.12
208
2
0.16
130
3
0.16
19200
208
0
0.16
164
1
–0.12
208
1
0.16
130
2
0.16
38400
104
0
0.16
164
0
–0.12
208
0
0.16
130
1
0.16
76800
52
0
0.16
82
0
–0.12
104
0
0.16
130
0
0.16
150000
27
0
–1.24
42
0
–0.16
53
0
0.63
67
0
–0.50
300000
13
0
2.56
21
0
–0.16
27
0
–1.24
33
0
1.01
1250000
–
–
–
5
0
0.64
–
–
–
8
0
0.00
Note
Only for the V850/SB1
Remark
f
XX
: Main clock oscillation frequency
f
XX
2
m+1
×
k