Question

求飞思卡尔单片机mc9s12xs128 超频CW5.0例程

原题：
理解锁相环的含义，用飞思卡尔单片机mc9s12xs128, 编程开发软件codewarrior5.0编写将单片机超频到16Mhz,24Mhz,32Mhz,64Mhz或80Mhz的小程序（代码段）。
R.T.求例程。

Answer 1

void MCUInit()
{
DisableInterrupts; //禁止总中断
CLKSEL &= 0x7f; //CLKSEL的第7位置0，选择系统时钟源为OSCCLK

PLLCTL &= 0xbf; //禁止PLL , PLLCTL.6(pllon)设为0;先关闭PLL
SYNR = 0x01; //根据需要的时钟频率设置SYNR和REFDV寄存器
REFDV = 0x00;
//PLLCLK=2*OSCCLK*(SYNR+1)/(REFDV+1)

PLLCTL |= (1<<6); //打开PLL , PLLCTL.6(pllon)设为1;开PLL
while (( CRGFLG&0x08) == 0x00);//通过判断LOCK位，
//确定PLL是否稳定
CLKSEL |= (1<<7); //时钟频率稳定后，允许锁相环时钟源作为系统时钟源；

//本句 执行后:BusClock=PLLCLK/2 BusClock = 32MHz
}
自己写的，调试过没问题，具体主线你想用多少根据注释自己改

Answer 2

给你一段demo,你还需要在自己的系统上调试验证
void SetBusCLK_16M(void)
{
CLKSEL=0X00; // disengage PLL to system
PLLCTL_PLLON=1; // turn on PLL
SYNR=0x00 | 0x01; // VCOFRQ[7:6];SYNDIV[5:0]
// fVCO= 2*fOSC*(SYNDIV + 1)/(REFDIV + 1)
// fPLL= fVCO/(2 × POSTDIV)
// fBUS= fPLL/2
// VCOCLK Frequency Ranges VCOFRQ[7:6]
// 32MHz <= fVCO <= 48MHz 00
// 48MHz < fVCO <= 80MHz 01
// Reserved 10
// 80MHz < fVCO <= 120MHz 11
REFDV=0x80 | 0x01; // REFFRQ[7:6];REFDIV[5:0]
// fREF=fOSC/(REFDIV + 1)
// REFCLK Frequency Ranges REFFRQ[7:6]
// 1MHz <= fREF <= 2MHz 00
// 2MHz < fREF <= 6MHz 01
// 6MHz < fREF <= 12MHz 10
// fREF > 12MHz 11
// pllclock=2*osc*(1+SYNR)/(1+REFDV)=32MHz;
POSTDIV=0x00; // 4:0, fPLL= fVCO/(2xPOSTDIV)
// If POSTDIV = $00 then fPLL is identical to fVCO (divide by
_asm(nop); // BUS CLOCK=16M
_asm(nop);
while(!(CRGFLG_LOCK==1)); //when pll is steady ,then use it;
CLKSEL_PLLSEL =1; //engage PLL to system;
}
void SetBusCLK_32M(void)
{
CLKSEL=0X00; // disengage PLL to system
PLLCTL_PLLON=1; // turn on PLL
SYNR =0x40 | 0x03; // pllclock=2*osc*(1+SYNR)/(1+REFDV)
=64MHz;
REFDV=0x80 | 0x01;
POSTDIV=0x00;
_asm(nop); // BUS CLOCK=32M
_asm(nop);
while(!(CRGFLG_LOCK==1)); //when pll is steady ,then use it;
CLKSEL_PLLSEL =1; //engage PLL to system;
}
void SetBusCLK_40M(void)
{
CLKSEL=0X00; //disengage PLL to system
PLLCTL_PLLON=1; //turn on PLL
SYNR =0xc0 | 0x04;
REFDV=0x80 | 0x01;
POSTDIV=0x00; //pllclock=2*osc*(1+SYNR)/(1+REFDV)=80MHz;
_asm(nop); //BUS CLOCK=40M
_asm(nop);
while(!(CRGFLG_LOCK==1)); //when pll is steady ,then use it;
CLKSEL_PLLSEL =1; //engage PLL to system;
}
void SetBusCLK_48M(void)
{
CLKSEL=0X00; //disengage PLL to system
PLLCTL_PLLON=1; //turn on PLL
SYNR =0xc0 | 0x05;
REFDV=0x80 | 0x01;
POSTDIV=0x00; //pllclock=2*osc*(1+SYNR)/(1+REFDV)=96MHz;
_asm(nop); //BUS CLOCK=48M
_asm(nop);
while(!(CRGFLG_LOCK==1)); //when pll is steady ,then use it;
CLKSEL_PLLSEL =1; //engage PLL to system;
}
void SetBusCLK_64M(void)
{
CLKSEL=0X00; //disengage PLL to system
PLLCTL_PLLON=1; //turn on PLL
SYNR =0xc0 | 0x07;
REFDV=0x80 | 0x01;
POSTDIV=0x00; //pllclock=2*osc*(1+SYNR)/(1+REFDV)=128MHz;
_asm(nop); //BUS CLOCK=64M
_asm(nop);
while(!(CRGFLG_LOCK==1)); //when pll is steady ,then use it;
CLKSEL_PLLSEL =1; //engage PLL to system;
}
void SetBusCLK_80M(void)
{
CLKSEL=0X00; //disengage PLL to system
PLLCTL_PLLON=1; //turn on PLL
SYNR =0xc0 | 0x09;
REFDV=0x80 | 0x01;
POSTDIV=0x00; //pllclock=2*osc*(1+SYNR)/(1+REFDV)=160MHz;
_asm(nop); //BUS CLOCK=80M
_asm(nop);
while(!(CRGFLG_LOCK==1)); //when pll is steady ,then use it;
CLKSEL_PLLSEL =1; //engage PLL to system;
}
void SetBusCLK_88M(void)
{
CLKSEL=0X00; //disengage PLL to system
PLLCTL_PLLON=1; //turn on PLL
SYNR =0xc0 | 0x0a;
REFDV=0x80 | 0x01;
POSTDIV=0x00; //pllclock=2*osc*(1+SYNR)/(1+REFDV)=176MHz;
_asm(nop); //BUS CLOCK=88M
_asm(nop);
while(!(CRGFLG_LOCK==1)); //when pll is steady ,then use it;
CLKSEL_PLLSEL =1; //engage PLL to system;
}
void SetBusCLK_96M(void)
{
CLKSEL=0X00; //disengage PLL to system
PLLCTL_PLLON=1; //turn on PLL
SYNR =0xc0 | 0x0b;
REFDV=0x80 | 0x01;
POSTDIV=0x00; //pllclock=2*osc*(1+SYNR)/(1+REFDV)=192MHz;
_asm(nop); //BUS CLOCK=96M
_asm(nop);
while(!(CRGFLG_LOCK==1)); //when pll is steady ,then use it;
CLKSEL_PLLSEL =1; //engage PLL to system;
}
void SetBusCLK_104M(void)
{
CLKSEL=0X00; //disengage PLL to system
PLLCTL_PLLON=1; //turn on PLL
SYNR =0xc0 | 0x0c;
REFDV=0x80 | 0x01;
POSTDIV=0x00; //pllclock=2*osc*(1+SYNR)/(1+REFDV)=208MHz;
_asm(nop); //BUS CLOCK=104M
_asm(nop);
while(!(CRGFLG_LOCK==1)); //when pll is steady ,then use it;
CLKSEL_PLLSEL =1; //engage PLL to system;
}
void SetBusCLK_120M(void)
{
CLKSEL=0X00; //disengage PLL to system
PLLCTL_PLLON=1; //turn on PLL
SYNR =0xc0 | 0x0d;
REFDV=0x80 | 0x01;
POSTDIV=0x00; //pllclock=2*osc*(1+SYNR)/(1+REFDV)=240MHz;
_asm(nop); //BUS CLOCK=120M
_asm(nop);
while(!(CRGFLG_LOCK==1)); //when pll is steady ,then use it;
CLKSEL_PLLSEL =1; //engage PLL to system;
}

追问

求注释。。。TAT

追答

已经注了

Answer 3

楼主好眼力。飞思的确很不错。