Renesas E100, User Manual, Page: 35 / 232

R0E417250MCU00 User
’s Manual
2. Setup
R20UT3587EJ0302 Rev.3.02 Page 35 of 232
Sep.01. 21
2.8.3 Using the Oscillator Circuit on the User System
To operate the MCU unit with an external clock source, construct the oscillator circuit as shown in Figure 2.8 in the user
system and input the oscillator output at 50% duty (within the operating range of the evaluation MCU) into pin EXTAL. Pin
XTAL, on the other hand, should be open. Choose "User" in the emulator debugger to use this clock source.
MCU
EXTAL XTAL
Open
Oscillator
circuit
Figure 2.8 External oscillator circuit
Make note that in the oscillator circuit shown in Figure 2.9 where an oscillator is connected between pins EXTAL and XTAL,
oscillation does not occur because a converter board and other devices are used between the evaluation MCU and the user
system.
MCU
EXTAL XTAL
Figure 2.9 Circuit in which oscillation does not occur
2.8.4 Using the Internal Generator Circuit
The dedicated circuit in the E100 can generate clock source of any frequency specified in the emulator debugger, and it can be
supplied as a main clock. It does not depend on the oscillator circuit board in the MCU unit or the oscillator circuit on the user
system. If you want to debug programs without the user system or change a frequency temporarily, you can check its operation
before purchasing an oscillator. If you want to use the internal generator circuit in the E100 to generate a main clock, choose
"Generate" in the emulator debugger and specify a frequency you like.
Although you can change a frequency between 1.0 and 99.9 MHz by 0.1 MHz for the E100, do not specify a value exceeding
the maximum input frequency 10 MHz for EXTAL of the MCU.
IMPORTANT
Note on Using the Internal Generator Circuit:
⚫
The internal generator circuit is equipped for temporary debugging purposes. Temperature characteristics of
frequencies are not guaranteed.
⚫
Be sure to evaluate your system with an oscillator whose frequency is the same as that of the oscillator module
or oscillator circuit (internal clock) for final evaluation purposes.