pll.c

嵌入式开发

/*
*********************************************************************************************************
* 文件: PLL.C
* 描述: 初始化 PLL.VPB.MAM 等功能部件,根据目标板的要求更改相应频率设置在 PLL.H 中.
* 编写: 深思 ([e-mail]).
*********************************************************************************************************
*/

#include "includes.h"

/*
********************************************************************************************************
* 函数: void PLLInit(void).
* 描述: 设置 PLL. VPB. MAM. 等功能器件.
********************************************************************************************************
*/
void PLLInit(void)
{
    PLLCON = 1;                                         /* PLL 使能.    */

#if ((Fcclk / 4) / Fpclk) == 1
    VPBDIV = 0;
#endif

#if ((Fcclk / 4) / Fpclk) == 2
    VPBDIV = 2;
#endif

#if ((Fcclk / 4) / Fpclk) == 4
    VPBDIV = 1;
#endif

#if (Fcco / Fcclk) == 2
    PLLCFG = ((Fcclk / Fosc) - 1) | (0 << 5);
#endif

#if (Fcco / Fcclk) == 4
    PLLCFG = ((Fcclk / Fosc) - 1) | (1 << 5);
#endif

#if (Fcco / Fcclk) == 8
    PLLCFG = ((Fcclk / Fosc) - 1) | (2 << 5);
#endif

#if (Fcco / Fcclk) == 16
    PLLCFG = ((Fcclk / Fosc) - 1) | (3 << 5);
#endif

    PLLFEED = 0xaa;
    PLLFEED = 0x55;                                     /* 馈送序列.        */
    while((PLLSTAT & (1 << 10)) == 0);                  /* 等待 PLL 锁定.   */
    PLLCON  = 3;
    PLLFEED = 0xaa;
    PLLFEED = 0x55;

    MAMCR = 2;                                          /* 设置存储器加速模块 */

#if Fcclk < 20000000
        MAMTIM = 1;
#else
    #if Fcclk < 40000000
        MAMTIM = 2;
    #else
        MAMTIM = 3;
    #endif
#endif

    VICIntEnClr     = 0x0ffffffff;                      /* 初始化VIC.       */
    VICSoftIntClear = 0x0ffffffff;
    VICVectAddr     = 0;
}

/*
*********************************************************************************************************
* END.
*********************************************************************************************************
*/