MC9S12DP512锁相环初始化程序 -

标题: MC9S12DP512锁相环初始化程序 [打印本页]

作者: xiaoou 时间: 2013-12-7 03:12
标题: MC9S12DP512锁相环初始化程序
void init_pll(void)
{
CRGINT = 0;                //关中断
CLKSEL_PLLSEL = 0;          //在未初始化PLL前不使用PLL的输出作为CPU时钟
#if(BUS_CLOCK == 40000000)
      SYNR = 4;
#elif(BUS_CLOCK == 32000000)
      SYNR = 7;
#elif(BUS_CLOCK == 24000000)
      SYNR = 2;
#endif
REFDV = 1;                //PLLCLK=2×OSCCLK×(SYNR+1)/(REFDV+1)=64MHz ,fbus=32M
PLLCTL_PLLON = 1;          //开PLL
PLLCTL_AUTO = 1;          //选取自动模式
while (CRGFLG_LOCK == 0); //等待PLL锁定频率
      CLKSEL_PLLSEL = 1;          //选择系统时钟由PLL产生,即总线时钟=PLLCLK/2
}

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