HD64F38602R Datasheet, PDF (99/552 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer

Section 4 Clock Pulse Generators
4.2.3 External Clock Input Method
Connect an external clock signal to pin OSC1, and leave pin OSC2 open. Figure 4.4 shows a
typical connection. The duty cycle of the external clock signal must be 45 to 55%.
OSC1
OSC2
Open
External clock input
Figure 4.4 Example of External Clock Input
4.2.4 On-Chip Oscillator Selection Method
The on-chip oscillator is selected by the E7_2 pin input level during a reset. The methods for
selecting the system clock oscillator and on-chip oscillator are shown in table 4.1. The input level
on the E7_2 pin during a reset is pulled up or down using a resistor according to the selected
oscillator, and fixed on exit from the reset state.
When the on-chip oscillator is selected, a resonator no longer needs to be connected to the OSC1
and OSC2 pins. In such a case, fix the OSC1 pin to GND or leave it open, and leave the OSC2 pin
open.
Notes: 1. When programming or erasing the flash memory, such as performing on-board
programming, the system clock oscillator must be selected. When the on-chip emulator
is used, even though the on-chip oscillator is selected, connect a resonator or input an
external clock.
2. When the on-chip debugger is connected, the value of the resistor should be high.
When not connected, it is specified according to the selected oscillator.
Table 4.1 Methods for Selecting System Clock Oscillator and On-Chip Oscillator
Oscillator in System Clock Pulse
E7_2 Pin Input Level (during Reset) Generator
0
On-chip oscillator
1
System clock oscillator
OSCF
1
0
Rev. 3.00 May 15, 2007 Page 67 of 518
REJ09B0152-0300