HD6473847RHV Datasheet, PDF (131/546 Pages) Renesas Technology Corp – Renesas 8-Bit Single-Chip Microcomputer H8 Family / H8/300L Super Low Power Series

Section 4 Clock Pulse Generators
4.3.3 External Clock Input Method
Connect an external clock signal to pin OSC1, and leave pin OSC2 open. Figure 4.7 shows a
typical connection. The duty cycle of the external clock signal must be 45 to 55%.
OSC1
OSC2
Open
External clock input
Figure 4.7 Example of External Clock Input
4.3.4 On-Chip Oscillator Selection Method (H8/38104 Group Only)
The on-chip oscillator is selected by setting the IRQAEC pin input level during resets*. The
IRQAEC pin input level set during resets must be fixed at V_CC or GND, based on the oscillator to
be selected. It is not necessary to connect an oscillator to pins OSC1 and OSC2 if the on-chip
oscillator is selected. In this case, pin OSC1 should be fixed at V_CC or GND.
Notes: The system clock oscillator must be selected in order to program or erase flash memory as
part of operations such as on-board programming. Also, when using the on-chip emulator,
an oscillator should be connected, or an external clock input, even if the on-chip oscillator
is selected.
* Other than watchdog timer or low-voltage detect circuit reset.
Table 4.2 System Clock Oscillator and On-Chip Oscillator Selection Methods
IRQAEC pin input level (during resets)
System clock oscillator
On-chip oscillator
0
Enabled
Disabled
1
Disabled
Enabled
Rev. 7.00 Mar. 08, 2010 Page 99 of 510
REJ09B0024-0700