NEC mPD789101 User Manual page 172

The baud rate transmit/receive clock to be generated is either a signal scaled from the system clock, or a signal
scaled from the clock input from the ASCK20 pin.
(a) Generation of baud rate transmit/receive clock by means of system clock
The transmit/receive clock is generated by scaling the system clock. The baud rate generated from the
system clock is estimated by using the following expression.
[Baud rate] =
: System clock oscillation frequency (ceramic/crystal oscillation)
f
X
Values in Figure 13-6 specified by the setting in TPS200 to TPS203 (2 ≤ n ≤ 8)
n:
Table 13-3. Example of Relationship between System Clock and Baud Rate
Baud Rate (bps)
1,200
2,400
4,800
9,600
19,200
38,400
76,800
172
CHAPTER 13 SERIAL INTERFACE 20
f
X
[Hz]
× 8
n + 1
2
n BRGC20 Set Value
8
7
6
5
4
3
2
User's Manual U13045EJ2V0UM00
Error (%)
f = 5.0 MHz
X
70H 1.73
60H
50H
40H
30H
20H
10H
f = 4.9152 MHz
X
0