MSP430时钟定性分析

墨蓝 2022-05-20 06:47 221阅读 0赞

MSP430时钟定性分析

# 1.时钟参数 #

# 1.1 宏定义时钟注释 #

//宏定义外接时钟，设置时钟很重要
    #define EXTAL_IN_XT1_HZ ( 32768)
    #define EXTAL_IN_XT2_HZ (4000000)
    //宏定义内部REFO，VLO时钟频率
    #define VLOCLK_FREQUENCY ( 10000)
    #define REFOCLK_FREQUENCY ( 32768)

## 1.2 时钟来源 ##

switch(clk)
     {
      case CLOCK_XT1    :g_sClock.CLK.nHZ = EXTAL_IN_XT1_HZ;break;
      case CLOCK_VLO    :g_sClock.CLK.nHZ = VLOCLK_FREQUENCY;break;
      case CLOCK_REFO   :g_sClock.CLK.nHZ = REFOCLK_FREQUENCY;break;       
      case CLOCK_DCO    :g_sClock.CLK.nHZ = g_sClock.DCO_FLL_Frequency;break;    
      case CLOCK_DCO_DIV:g_sClock.CLK.nHZ = g_sClock.DCO_FLL_Frequency;break;
      case CLOCK_XT2    :g_sClock.CLK.nHZ = EXTAL_IN_XT2_HZ;break;
      default :return;
     }

## 1.3 时钟参数介绍 ##

typedef enum
    {
      CLOCK_XT1,        //XT1 
      CLOCK_VLO,        //内部10K
      CLOCK_REFO,       //内部32768
      CLOCK_DCO, //内部DCO,如果使用内部DCO作为时钟的话，需要先调用DCO_PLLConfig设置DCO频率
      CLOCK_DCO_DIV,   //DCO分频(分频为1且不允许修改，与DCO同频)
      CLOCK_XT2,       //XT2
    }CLOCK_Source;     //时钟源

## 1.4 时钟分表 ##

<table> 
 <thead> 
  <tr> 
   <th>时钟源</th> 
   <th align="right">时钟频率(HZ)</th> 
   <th align="center">时钟源</th> 
   <th align="center">时钟频率(Hz)</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>CLOCK_XT1</td> 
   <td align="right">32768(32.768k)</td> 
   <td align="center">CLOCK_DCO</td> 
   <td align="center">自主设置倍频</td> 
  </tr> 
  <tr> 
   <td>CLOCK_VLO</td> 
   <td align="right">10000(10k)</td> 
   <td align="center">CLOCK_DCO_DIV</td> 
   <td align="center">同CLOCK_DCO</td> 
  </tr> 
  <tr> 
   <td>CLOCK_REFO</td> 
   <td align="right">32768(32.768k)</td> 
   <td align="center">CLOCK_XT2</td> 
   <td align="center">4000000(4M)</td> 
  </tr> 
 </tbody> 
</table>

# 2.频率配置过程 #

## 2.1 *XT1*时钟配置初始化 ##

/*******************************************************************************
    * 函数名称：XT1_Config(STATUS status)
    * 功能说明：设置是否使能XT1
    * 参数说明：STATUS status：是否使能XT1
    * 函数返回：无
    * 使用示例：XT1_Config(ENABLE);   //使能XT1
    ********************************************************************************/
    static inline void XT1_Config(STATUS status)
    {
      if(status != DISABLE)
      {
     if(UCS->XT1_OFF == BIT_SET)
     { 
     GPIO_MultiBits_Init(P5,(GPIO_Pin_4|GPIO_Pin_5),GPI|SEL); //选用 XT1 第二功能
     UCS->XT1_OFF = RESET ; // 开启 XT1 
     do
     { 
     UCS->XT1_LFOFFG = RESET; // 清除XT1,CLOCK_DCO 失效标志 
     SFRIFG1 &= ~OFIFG; //
     }while (UCS->XT1_LFOFFG == BIT_SET); //
     }
      }
      else
      {
     UCS->XT1_OFF = BIT_SET ; // 关闭 XT1 
      }
    }

## 2.2 *XT2*时钟配置初始化 ##

/*******************************************************************************
    * 函数名称：XT2_Config(STATUS status)
    * 功能说明：设置是否使能XT2
    * 参数说明：STATUS status：是否使能XT2
    * 函数返回：无
    * 使用示例：XT2_Config(TRUE);   //使能XT2
    ********************************************************************************/
    static inline void XT2_Config(STATUS status)
    {
      if(status != DISABLE)
      {
     if(UCS->XT2_OFF == BIT_SET)
     { 
     GPIO_MultiBits_Init(P5,(GPIO_Pin_2|GPIO_Pin_3),GPI|SEL); //选用 CLOCK_XT2 第二功能
     UCS->XT2_OFF = RESET; //开启 CLOCK_XT2 
     do
     { 
     UCS->XT2_OFFG = RESET;
     SFRIFG1 &= ~OFIFG; 
     }while (UCS->XT2_OFFG == BIT_SET);
     }
      }
      else
      {
     UCS->XT2_OFF = BIT_SET ; // 关闭XT2 
      }
    
    }

## 2.3 内部时钟 ##

*CLOCK\_VLO*，*CLOCK\_REFO*为内部时钟源，不需要配置和初始化。

## 2.4 DCO及DCO\_DIV配置过程 ##

由于DCO是可以自主倍频的，倍频函数为*CLOCK\_DCO\_PLLConfig(FLLREF\_Source, FLLREF\_DIVx, uint32\_t DCO\_FLL\_Fre)*，由于*DCO\_DIV*分频为1且不允许修改，即*DCO\_DIV*与*DCO*同频，下面好好分析一下倍频过程

### 2.4.1 时钟分频系数，共计6种选择 ###

typedef enum
    {
      FLLREF_DIV_1     ,   //不分频
      FLLREF_DIV_2     ,   //二分频
      FLLREF_DIV_4     ,   //四分频
      FLLREF_DIV_8     ,   //八分频
      FLLREF_DIV_12    ,   //十二分频
      FLLREF_DIV_16    ,   //十六分频
    }FLLREF_DIVx;    //FLL参考时钟分频

### 2.4.2 参考分频时钟，总计3个 ###

typedef enum
    {
      FLLREF_XT1    =0u,    //32.768k
      FLLREF_REFO   =2u,    //10k
      FLLREF_XT2    =5u     //4M
    }FLLREF_Source;  //FLL参考时钟源

### 2.4.3 倍频函数 ###

/******************************************************************************* * 函数名称：CLOCK_DCO_PLLConfig(FLLREF_Source refsource, FLLREF_DIVx refdiv, uint32_t DCO_FLL_Fre) * 功能说明：设置DCO频率，单位（HZ） * 参数说明：FLLREF_Source refsource :参考时钟源 FLLREF_DIVx refdiv :参考时钟源分频系数 uint32_t DCO_FLL_Fre :DCO设置频率 * 函数返回：无 ********************************************************************************/
    void CLOCK_DCO_PLLConfig     (FLLREF_Source refsource, FLLREF_DIVx refdiv, uint32_t DCO_FLL_Fre)
    {
      static const uint16_t ref_div_value[6]={
       1,2,4,8,12,16};
      /*根据频率提高内核电压*/
      //SetVcoreUp ( (DCO_FLL_Fre < 12MHz) ? 0 : ((DCO_FLL_Fre < 16MHz) ? 1 : ((DCO_FLL_Fre < 20MHz) ? 2 :3))); //设置内核电压
      if(DCO_FLL_Fre < 12MHz)
        SetVcoreUp (0x00);                      //设置内核电压
      else if(DCO_FLL_Fre < 16MHz)
        SetVcoreUp (0x01);       
      else if(DCO_FLL_Fre < 20MHz)
        SetVcoreUp (0x02);       
      else
        SetVcoreUp (0x03);       
    
      __bis_SR_register(SCG0);                  // 禁止倍频环FLL,
      UCS->CTL0 = 0x0000;                       // 清零 DCOx, MODx
    
      if (DCO_FLL_Fre < 0.63MHz)         // fsystem < 0.63MHz
        UCS->DCORSEL = 0;
      else if (DCO_FLL_Fre < 1.25MHz)    // 0.63MHz < fsystem < 1.25MHz
        UCS->DCORSEL = 1;
      else if (DCO_FLL_Fre < 2.5MHz)     // 1.25MHz < fsystem < 2.5MHz
        UCS->DCORSEL = 2;
      else if (DCO_FLL_Fre <   5MHz)     // 2.5MHz < fsystem < 5MHz
        UCS->DCORSEL = 3;
      else if (DCO_FLL_Fre <  10MHz)     // 5MHz < fsystem < 10MHz
        UCS->DCORSEL = 4;
      else if (DCO_FLL_Fre <  20MHz)     // 10MHz < fsystem < 20MHz
        UCS->DCORSEL = 5;
      else if (DCO_FLL_Fre <  40MHz)     // 20MHz < fsystem < 40MHz
        UCS->DCORSEL = 6;
      else
        UCS->DCORSEL = 7;
    
      UCS->FLLREFDIV = refdiv;
      UCS->SELREF = refsource;
    
      float Fref_value;
      if(refsource == FLLREF_XT2)
      {
        XT2_Config(TRUE);
        Fref_value = (float)((uint32_t)EXTAL_IN_XT2_HZ/ref_div_value[refdiv]);  
      }
      else if(refsource == FLLREF_XT1)
      {
        XT1_Config(TRUE);
        Fref_value = (float)(EXTAL_IN_XT1_HZ/ref_div_value[refdiv]);
      }
      else if(refsource == FLLREF_REFO)
      {
        Fref_value = (float)(REFOCLK_FREQUENCY/ref_div_value[refdiv]);
      }
      uint16_t FLLN_VALUE = (uint16_t)((DCO_FLL_Fre/Fref_value+0.5f)-1u);
      ASSERT(FLLN_VALUE < 1024,"CLOCK_DCO_PLLConfig","FLLN_VALUE不允许超过1023，请将DCO频率设低或者更换为更高频率的参考时钟源！");         //不允许超过1023，请将DCO频率设低或者更换为更高频率的参考时钟源
    
      g_sClock.DCO_FLL_Frequency = DCO_FLL_Fre;
    
      UCS->FLLN = FLLN_VALUE;        //
      UCS->FLLD = 0;     //设置DCO分频 
    
      __bic_SR_register(SCG0);                  // 使能FLL
      do
      {
        UCS->DCO_FFG = RESET; // 清除,CLOCK_DCO 失效标志 
        SFRIFG1 &= ~OFIFG;                                             // 清除时钟失效标志
      }while (UCS->DCO_FFG == BIT_SET);                                           // 检查DCO失效标志
      //将使用DCO作为时钟源的时钟频率值修改
      if(UCS->SELM == CLOCK_DCO || UCS->SELM == CLOCK_DCO_DIV)
      {
        CLOCK_DIVx div = (CLOCK_DIVx)UCS->DIVM;
        CLOCK_MCLK_Config ((CLOCK_Source)UCS->SELM, div);
      }
    
      if(UCS->SELS == CLOCK_DCO || UCS->SELS == CLOCK_DCO_DIV)
      {
        CLOCK_DIVx div = (CLOCK_DIVx)UCS->DIVS;
        CLOCK_SMCLK_Config((CLOCK_Source)UCS->SELS, div);
      }
    
      if(UCS->SELA == CLOCK_DCO || UCS->SELA == CLOCK_DCO_DIV)
      {
        CLOCK_DIVx div = (CLOCK_DIVx)UCS->DIVA;
        CLOCK_ACLK_Config ((CLOCK_Source)UCS->SELS, div);
      }
    }

## 2.5 通过案例分析总结关键步骤 ##

使用示例：

> CLOCK\_DCO\_PLLConfig(FLLREF\_REFO, FLLREF\_DIV\_1, 16MHZ);  
> //设置DCO倍频环以REFO的一分频作为参考时钟源，倍频到16MHZ

1. 传入参数，分别传入参考时钟源FLLREF_REFO，分频系数FLLREF_DIV_1，所要倍频数
    2. 根据时钟源选择内核电压，这里SetVcoreUp (0x02); UCS->DCORSEL = 5;
    3. 确定时钟来源，计算参考频率，这里 Fref_value = 32768
    4. 确定锁相环PLLN_VALUE值，这里PLLN_VALUE=487
    5. 更新配置参数得到所要时钟频率

## 2.6 内核电压设置函数 ##

/*******************************************************************************
    函数功能：设置内核电压值（与频率设置有关）
    函数参数：u8 level ：电压阶梯 小于3
    ********************************************************************************/
    void SetVcoreUp (uint8_t level)
    {
    #if 1 //仿真时修改为0，否则会卡在死循环里
      // Open PMM registers for write
      PMMCTL0_H = PMMPW_H;              
      // Set SVS/SVM high side new level
      SVSMHCTL = SVSHE + SVSHRVL0 * level + SVMHE + SVSMHRRL0 * level;
      // Set SVM low side to new level
      SVSMLCTL = SVSLE + SVMLE + SVSMLRRL0 * level;
      // Wait till SVM is settled
      uint16_t i=50000;
      while (((PMMIFG & SVSMLDLYIFG) == 0)&&((i--)>0));
      // Clear already set flags
      PMMIFG &= ~(SVMLVLRIFG + SVMLIFG);
      // Set VCore to new level
      PMMCTL0_L = PMMCOREV0 * level;
      // Wait till new level reached
      i =50000;
      if ((PMMIFG & SVMLIFG))
     while(((PMMIFG & SVMLVLRIFG) == 0)&&((i--)>0));
      /*
      if ((PMMIFG & SVMLIFG))
     while ((PMMIFG & SVMLVLRIFG) == 0);
      */
      // Set SVS/SVM low side to new level
      SVSMLCTL = SVSLE + SVSLRVL0 * level + SVMLE + SVSMLRRL0 * level;
      // Lock PMM registers for write access
      PMMCTL0_H = 0x00;
    #endif
    }

# 3.各时钟输出 #

#define MCLK_OUT()                              GPIO_Init(P7,7,GPO | SEL)       //主时钟输出, P7.7
    #define SMCLK_OUT()                             GPIO_Init(P2,2,GPO | SEL)       //子系统时钟输出P2.2
    #define ACLK_OUT()                              GPIO_Init(P1,0,GPO | SEL)       //辅助时钟输出 P1.0 
    #define CLOCK_OUT()                             do{
       MCLK_OUT();SMCLK_OUT();ACLK_OUT();}while(0)  //所有时钟输出

## 3.1 设置主时钟源 ##

/*************************************************************************
    * 函数名称：CLOCK_MCLK_Config  (CLOCK_Source mclk , CLOCK_DIVx mclk_div)
    * 功能说明：设置主时钟源及分频
    * 参数说明：CLOCK_Source mclk   :主时钟时钟源
     CLOCK_DIVx mclk_div :主时钟分频系数
    * 函数返回：无
    * 使用示例：CLOCK_MCLK_Config  (CLOCK_DCO , DIV_1);   //主时钟使用DCO作为时钟源，分频系数为1（不分频）
    *************************************************************************/  
    void CLOCK_MCLK_Config  (CLOCK_Source mclk , CLOCK_DIVx mclk_div)
    {
      if(mclk == CLOCK_XT2)
      {
     XT2_Config(TRUE);
      }
      else if(mclk == CLOCK_XT1)
      {
     XT1_Config(TRUE);
      }
    
      UCS->SELM = mclk;                         //选择DCO作为时钟源
      UCS->DIVM = mclk_div;
    
      switch(mclk)
      {
      case CLOCK_XT1 :g_sClock.MCLK.nHZ = EXTAL_IN_XT1_HZ;break;
      case CLOCK_VLO :g_sClock.MCLK.nHZ = VLOCLK_FREQUENCY;break;
      case CLOCK_REFO :g_sClock.MCLK.nHZ = REFOCLK_FREQUENCY;break;       
      case CLOCK_DCO :g_sClock.MCLK.nHZ = g_sClock.DCO_FLL_Frequency;break;    
      case CLOCK_DCO_DIV:g_sClock.MCLK.nHZ = g_sClock.DCO_FLL_Frequency;break;
      case CLOCK_XT2 :g_sClock.MCLK.nHZ = EXTAL_IN_XT2_HZ;break;
      default :return;
      }
      g_sClock.MCLK.nHZ >>= mclk_div;
      g_sClock.MCLK.nKHZ = g_sClock.MCLK.nHZ/1000u;
      g_sClock.MCLK.fMHZ = g_sClock.MCLK.nHZ/1000000.0;
    }

## 3.2 设置系统时钟源 ##

/*************************************************************************
    * 函数名称：CLOCK_SMCLK_Config (CLOCK_Source smclk, CLOCK_DIVx smclk_div)
    * 功能说明：设置系统时钟源及分频
    * 参数说明：CLOCK_Source smclk   :系统时钟时钟源
     CLOCK_DIVx smclk_div :系统时钟分频系数
    * 函数返回：无
    * 使用示例：CLOCK_SMCLK_Config  (CLOCK_DCO , DIV_2);   //系统时钟使用DCO作为时钟源，分频系数为2（二分频）
    *************************************************************************/  
    void CLOCK_SMCLK_Config (CLOCK_Source smclk, CLOCK_DIVx smclk_div)
    {
      if(smclk == CLOCK_XT2)
      {
     XT2_Config(TRUE);
      }
      else if(smclk == CLOCK_XT1)
      {
     XT1_Config(TRUE);
      }
    
      UCS->SELS = smclk;//选择smclk时钟源
      UCS->DIVS = smclk_div;
    
      switch(smclk)
      {
      case CLOCK_XT1 :g_sClock.SMCLK.nHZ = EXTAL_IN_XT1_HZ;break;
      case CLOCK_VLO :g_sClock.SMCLK.nHZ = VLOCLK_FREQUENCY;break;
      case CLOCK_REFO :g_sClock.SMCLK.nHZ = REFOCLK_FREQUENCY;break;       
      case CLOCK_DCO :g_sClock.SMCLK.nHZ = g_sClock.DCO_FLL_Frequency;break;
      case CLOCK_DCO_DIV:g_sClock.SMCLK.nHZ = g_sClock.DCO_FLL_Frequency;break;
      case CLOCK_XT2 :g_sClock.SMCLK.nHZ = EXTAL_IN_XT2_HZ;break;
      default :return;
      }
      g_sClock.SMCLK.nHZ >>= smclk_div;
      g_sClock.SMCLK.nKHZ = g_sClock.SMCLK.nHZ/1000u;;
      g_sClock.SMCLK.fMHZ = g_sClock.SMCLK.nHZ/1000000.0;
    }

## 3.3 设置辅助时钟源 ##

/*************************************************************************
    * 函数名称：CLOCK_ACLK_Config  (CLOCK_Source aclk , CLOCK_DIVx aclk_div)
    * 功能说明：设置辅助时钟源及分频
    * 参数说明：CLOCK_Source aclk   :辅助时钟时钟源
     CLOCK_DIVx aclk_div :辅助时钟分频系数
    * 函数返回：无
    * 使用示例：CLOCK_ACLK_Config  (XT! , DIV_4);   //辅助时钟使用XT1作为时钟源，分频系数为4（四分频）
    *************************************************************************/  
    void CLOCK_ACLK_Config  (CLOCK_Source aclk , CLOCK_DIVx aclk_div)
    {
       if(aclk == CLOCK_XT2)
      {
     XT2_Config(TRUE);
      }
      else if(aclk == CLOCK_XT1)
      {
     XT1_Config(TRUE);
      }
    
      UCS->SELA = aclk;//选择时钟源                   
      UCS->DIVA = aclk_div; //设置分频系数为0
    
      switch(aclk)
      {
      case CLOCK_XT1 :g_sClock.ACLK.nHZ = EXTAL_IN_XT1_HZ;break;
      case CLOCK_VLO :g_sClock.ACLK.nHZ = VLOCLK_FREQUENCY;break;
      case CLOCK_REFO :g_sClock.ACLK.nHZ = REFOCLK_FREQUENCY;break;       
      case CLOCK_DCO :g_sClock.ACLK.nHZ = g_sClock.DCO_FLL_Frequency;break;   
      case CLOCK_DCO_DIV:g_sClock.ACLK.nHZ = g_sClock.DCO_FLL_Frequency;break;
      case CLOCK_XT2 :g_sClock.ACLK.nHZ = EXTAL_IN_XT2_HZ;break;
      default :return;
      }
      g_sClock.ACLK.nHZ >>= aclk_div;
      g_sClock.ACLK.nKHZ = g_sClock.ACLK.nHZ/1000u;;
      g_sClock.ACLK.fMHZ = g_sClock.ACLK.nHZ/1000000.0;
    }

# 4.更改时钟来源操作 #

具体路径请改变msp430f5529\_system.h里面的宏定义修改时钟源及时钟分频

//宏定义初始化时钟频率及时钟源
    #define FLL_REF FLLREF_REFO //FLL参考时钟源
    #define FLLREF_DIV FLLREF_DIV_1 //FLL参考时钟分频系数
    #define DCO_CLK_HZ 25MHZ //DCO时钟频率
    //主时钟设置
    #define MCLK_SOURCE CLOCK_DCO //主时钟时钟源
    #define MCLK_DIV CLOCK_DIV_1 //主时钟时钟分频系数
    //系统时钟设置
    #define SMCLK_SOURCE CLOCK_XT2 //系统时钟时钟源
    #define SMCLK_DIV CLOCK_DIV_1 //系统时钟分频系数
    //辅助时钟设置
    #define ACLK_SOURCE CLOCK_REFO //辅助时钟时钟源
    #define ACLK_DIV CLOCK_DIV_1 //辅助时钟分频系数

# 5.时钟图 #

![1][]

[1]: /images/20220520/2062939f0c2d4bf4abf6715b261d631d.png