System Clock Generator - Renesas H8 Series Hardware Manual

Section 4 Clock Pulse Generators
Bit 2—IRQAEC Flag (IRQAECF)
This bit indicates the IRQAEC pin input level set during resets.
Bit 2
IRQAECF Description
0 IRQAEC pin set to GND during resets
1 IRQAEC pin set to V
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
H8/38024R Group, and figure 4.3(2) shows a typical method of connecting a crystal oscillator to
the H8/38024S and H8/38124 Group.
Rev. 7.00 Mar 10, 2005 page 106 of 652
REJ09B0042-0700
during resets
CC