Renesas H8/38024 Series, Hardware Manual

Page: 134 / 661

Rev. 6.00, 08/04, page 104 of 628
Bit 1—OSC Flag (OSCF)
This bit indicates the oscillator operating with the system clock pulse generator.
Bit 1
OSCF
Description
0 System clock oscillator operating (on-chip oscillator stopped)
1 On-chip oscillator operating (system clock oscillator stopped)
Bit 0—Reserved
This bit is reserved. Never write 1 to this bit, as it can cause the LSI to malfunction.
4.2 System Clock Generator
Clock pulses can be supplied to the system clock divider either by connecting a crystal or ceramic
oscillator, or by providing external clock input. As shown in figure 4.2, the H8/38124 Group
supports selection between a system clock oscillator and an on-chip oscillator. See section 4.2,
On-Chip Oscillator Selection Method, for information on selecting the on-chip oscillator.
Connecting a Crystal Oscillator
Figure 4.3(1) shows a typical method of connecting a crystal oscillator to the H8/38024 or
H8/38024F-ZTAT Group, and figure 4.3(2) shows a typical method of connecting a crystal
oscillator to the H8/38024S and H8/38124 Group.
C
1
C
2
OSC
1
OSC
2
R = 1 M
±
20%
f
Ω
R
f
Frequency
Note: Circuit constants should be determined in
consultation with the resonator manufacturer.
Crystal
oscillator
C
1
, C
2
Recommendation
value
12 pF
±
20% NDK 4.19 MHz
Figure 4.3(1) Typical Connection to Crystal Oscillator
(H8/38024, H8/38024F-ZTAT Group)