[求助] 一段F28027的ePWM模块的初始化程序-TI中文支持网

//Time Base SubModule Register
      (*ePWM[n+1]).TBCTL.bit.PRDLD = TB_SHADOW;//SHADOW模式
      (*ePWM[n+1]).TBPRD = period-1; //
      (*ePWM[n+1]).TBPHS.half.TBPHS = 0;       //
      (*ePWM[n+1]).TBCTR = 0; //

      (*ePWM[n+1]).TBCTL.bit.CTRMODE = TB_COUNT_UP;  //增计数模式
      (*ePWM[n+1]).TBCTL.bit.PHSEN = TB_ENABLE;//
      (*ePWM[n+1]).TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // Sync "flow through" mode 0
                              //These bits select the source of the EPWMxSYNCO signal.

(*ePWM[n+1]).TBCTL.bit.HSPCLKDIV = TB_DIV1;
(*ePWM[n+1]).TBCTL.bit.CLKDIV = TB_DIV1; //

      // Counter compare submodule registers
      (*ePWM[n+1]).CMPA.half.CMPA = period + 10;                      // Initial value
      (*ePWM[n+1]).CMPB = 20;                                                       // Initial value
      (*ePWM[n+1]).CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
      (*ePWM[n+1]).CMPCTL.bit.SHDWAMODE = CC_SHADOW;
      (*ePWM[n+1]).CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
      (*ePWM[n+1]).CMPCTL.bit.SHDWBMODE = CC_SHADOW;



      // Action Qualifier SubModule Registers
      (*ePWM[n+1]).AQCTLA.bit.CAU = AQ_SET;
      (*ePWM[n+1]).AQCTLA.bit.CBU = AQ_CLEAR;
      (*ePWM[n+1]).AQCTLA.bit.ZRO = AQ_CLEAR;
      (*ePWM[n+1]).AQCTLA.bit.PRD = AQ_CLEAR;

      (*ePWM[n+1]).AQCTLB.bit.CBU = AQ_SET;
      (*ePWM[n+1]).AQCTLB.bit.CAU = AQ_CLEAR;
      (*ePWM[n+1]).AQCTLB.bit.ZRO = AQ_CLEAR;
      (*ePWM[n+1]).AQCTLB.bit.PRD = AQ_CLEAR;
这里面CMPA的值period + 10，大于了TBPRD的周期值，那么这个比较值还起作用吗？如果不起作用，接下来的AQCTLA的设置是什么功能？如果起作用，其是怎么动作的呢？

Victor Zheng：

PWM的CMPA的值大于周期值因该是无效的。这是哪里来的程序

(*ePWM[n+1]).TBCTL.bit.HSPCLKDIV = TB_DIV1;
(*ePWM[n+1]).TBCTL.bit.CLKDIV = TB_DIV1; //

Martin Yu：

CMPA肯定不起作用，也许是特意初始化的时候不需要发生比较事件，注意查看下后面是否有对该寄存器进行再次配置的。

(*ePWM[n+1]).TBCTL.bit.HSPCLKDIV = TB_DIV1;
(*ePWM[n+1]).TBCTL.bit.CLKDIV = TB_DIV1; //

RUOF MA：

回复 Martin Yu:

谢谢两位，它后面的代码是这样的，

// Cycle-by-cycle shutdown mechanism configuration

EALLOW; //=========================================================================== // Define an event (DCAEVT1) based on Comparator 1 Output (*ePWM[n+1]).DCTRIPSEL.bit.DCAHCOMPSEL = DC_COMP1OUT; // DCAH = Comparator 1 output

(*ePWM[n+1]).TZDCSEL.bit.DCAEVT1 = TZ_DCAH_HI; // DCAEVT1 = DCAH high(will become active // as Comparator output goes high)

(*ePWM[n+1]).DCACTL.bit.EVT1SRCSEL = DC_EVT_FLT; // DCAEVT1 = DC_EVT_FLT (filtered)

(*ePWM[n+1]).DCACTL.bit.EVT1FRCSYNCSEL = DC_EVT_ASYNC; // Take async path

// Enable DCAEVT1 as a one-shot source

(*ePWM[n+1]).TZSEL.bit.DCAEVT1 = 1; // Enable One-Shot Trip

// Following code for the sync mechanism based on the same trigger event – COMPxOUT

(*ePWM[n+1]).DCACTL.bit.EVT1SYNCE = 1; // Sync enabled

// What do we want the DCAEVT1 event to do? – Initial Configuration

(*ePWM[n+1]).TZCTL.bit.TZA = TZ_NO_CHANGE; // EPWMxA – no change

(*ePWM[n+1]).TZCTL.bit.TZB = TZ_FORCE_LO; // EPWMxB – go low

后面只对EPWM2B作用了，难道标红的语句对EPWM2A也有操作吗？求解答，非常感谢

(*ePWM[n+1]).TBCTL.bit.HSPCLKDIV = TB_DIV1;
(*ePWM[n+1]).TBCTL.bit.CLKDIV = TB_DIV1; //

Johnson Chen1：

回复 RUOF MA:

楼主你好，

这样初始化的目的只是为了保证CMPA和CMPB比较事件发生不了，因此PWM输出将不会翻转，从而PWM输出保持在你希望的状态。

之后程序会根据算法来更新比较值CMPA或者CMPB，

(*ePWM[n+1]).TBCTL.bit.HSPCLKDIV = TB_DIV1;
(*ePWM[n+1]).TBCTL.bit.CLKDIV = TB_DIV1; //

Martin Yu：

回复 RUOF MA:

楼至，这段是数字比较模块的初始化配置文件，跟比较寄存器配置（PWM占空比改变）无关，楼主主要找下主循环开始之前的启动动作时是否有对CMPAHR是否有重新赋值的。

[求助] 一段F28027的ePWM模块的初始化程序

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