system.h

来自「在51下的外挂硬盘和FLASH的MP3方案程序以及原理图」· C头文件 代码 · 共 22 行

void InitPLL(void);

void InitPLL(void)
{
//  for 20MHz to 192MHz   R=96-1 0x5f  N=10-1  0x09

	PLLNDIV=0x09;					//set N
	PLLRDIV=0x5f;
	PLLCON=(PLLRDIV&0x03)<<6;		//set R0..1
	PLLRDIV=PLLRDIV>>2;				//set R2..9
	PLLCON=PLLCON&0xf7;				//clear PLLRES bit
	PLLCON=PLLCON|0x02;				//set PLLEN bit
	#ifdef DEBUG
		printf("waiting for PLL running...");
	#endif
	while (!(PLLCON&0x01));
	#ifdef DEBUG
		printf("ok\n");
	#endif
}