It is proposed to use crystal when simulation, the actual chip with RC oscillator circuit way to develop.

First of all, calculate external crystal and RC oscillator parameters according to chip operating frequency, plug crystal into emulator, re-compiler the program when simulation process passed, modify High_Clk option to RC, after the chip be programmed, adjust RC oscillator component parameters on target board until it meets the requirements.

In order to adjust RC component parameters conveniently, you can use an idle I/O port to output a fixed frequency square wave, so use the oscilloscope waveform to adjust RC parameters, and also facilitate the production of debugging. If no idle I/O port can be used, you can write a simple test program, program chips to adjust.