eCAP

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#include "DSP28x_Project.h"     // Device Headerfile and Examples Include File#include "DSP2833x_ECap_defines.h"#define EPWM1_TIMER_TBPRD  3750  // Period register 系统始终为150MHZ，下面的程序进行了4分频，即为37.5MHZ,这样得到的是10KHZUint32  TS1 = 0;Uint32  TS2 = 0;Uint32  TS3 = 0;Uint32  TS4 = 0;Uint32 PEROID = 0;Uint32 DUTY1 = 0;Uint32 DUTY2 = 0;Uint32 initcount = 0;Uint32 duty = 3750 / 2;__interrupt void ecap1_isr(void);void PWM1_Init()//初始化PWM{    EALLOW;    SysCtrlRegs.PCLKCR1.bit.ECAP1ENCLK = 1;;      // Stop all the TB clocks    EDIS;    // Setup TBCLK    EPwm1Regs.TBPRD = EPWM1_TIMER_TBPRD;           // 设置周期    EPwm1Regs.TBPHS.half.TBPHS = 0x0000;           // 如果使能的话，当有同步信号时，会将这个值赋值给CTR    EPwm1Regs.TBCTR = 0x0000;                      // 计数器初始值赋值为0    // Setup counter mode    EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; //计数模式    EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;        // Disable phase loading    EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV2;       // 这里是进行2分频    EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV2;          //这里也是2分频    EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_CTR_ZERO;    // Setup shadowing    EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;    //采用影子寄存器跟新    EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;    EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;  // Load on Zero    EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;    // Set actions    EPwm1Regs.AQCTLA.bit.CAU = AQ_CLEAR;            // Set PWM1A on event A, up count    EPwm1Regs.AQCTLA.bit.CAD = AQ_SET;              // Clear PWM1A on event A, down count    EPwm1Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE;    EPwm1Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC;    EPwm1Regs.DBFED = 50;    EPwm1Regs.DBRED = 50;    EPwm1Regs.CMPA.half.CMPA = (EPWM1_TIMER_TBPRD >> 1);}void Pwm_Init(){    /*首先进行的是PWM1引脚的初始化，因为PWM1的引脚为GPIO0和GPIO1，这两个引脚可以是普通的IO口，也可以复用输出PWM，这里选用复用功能*/    EALLOW;    GpioCtrlRegs.GPAPUD.bit.GPIO0 = 0;    // Enable pull-up on GPIO0 (EPWM1A)    GpioCtrlRegs.GPAPUD.bit.GPIO1 = 0;    // Enable pull-up on GPIO1 (EPWM1B)    GpioCtrlRegs.GPAMUX1.bit.GPIO0 = 1;   // Configure GPIO0 as EPWM1A复用功能设置，为0代表是普通IO口    GpioCtrlRegs.GPAMUX1.bit.GPIO1 = 1;   // Configure GPIO1 as EPWM1B    EDIS;    EALLOW;    SysCtrlRegs.PCLKCR0.bit.TBCLKSYNC = 0;      // Stop all the TB clocks    EDIS;    PWM1_Init();    EALLOW;    SysCtrlRegs.PCLKCR0.bit.TBCLKSYNC = 1;         // Start all the timers synced    EDIS;}void InitECapture(){   ECap1Regs.ECEINT.all = 0x0000;             // Disable all capture interrupts   ECap1Regs.ECCLR.all = 0xFFFF;              // Clear all CAP interrupt flags   ECap1Regs.ECCTL1.bit.CAPLDEN = 0;          // Disable CAP1-CAP4 register loads   ECap1Regs.ECCTL2.bit.TSCTRSTOP = EC_STOP;        // Make sure the counter is stopped   // Configure peripheral registers   ECap1Regs.ECCTL2.bit.CONT_ONESHT = EC_CONTINUOUS;      // One-shot/continuous   ECap1Regs.ECCTL2.bit.STOP_WRAP = 3;                  // Stop at 4 events（每4次进一次中断）   ECap1Regs.ECCTL1.bit.CAP1POL = EC_RISING;          // Rising edge   ECap1Regs.ECCTL1.bit.CAP2POL = EC_FALLING;          // Rising edge   ECap1Regs.ECCTL1.bit.CAP3POL = EC_RISING;          // Rising edge   ECap1Regs.ECCTL1.bit.CAP4POL = EC_FALLING;          // Rising edge   ECap1Regs.ECCTL1.bit.CTRRST1 = EC_ABS_MODE;          // Difference operation   ECap1Regs.ECCTL1.bit.CTRRST2 = EC_ABS_MODE;          // Difference operation   ECap1Regs.ECCTL1.bit.CTRRST3 = EC_ABS_MODE;          // Difference operation   ECap1Regs.ECCTL1.bit.CTRRST4 = EC_ABS_MODE;          // Difference operation   ECap1Regs.ECCTL2.bit.SYNCI_EN = EC_DISABLE;         // Enable sync in   ECap1Regs.ECCTL2.bit.SYNCO_SEL = EC_SYNCO_DIS;        // Pass through   ECap1Regs.ECCTL1.bit.CAPLDEN = EC_ENABLE;          // Enable capture units   ECap1Regs.ECCTL1.bit.PRESCALE = EC_DIV1;   ECap1Regs.ECCTL2.bit.CAP_APWM = EC_CAP_MODE;   ECap1Regs.ECCTL2.bit.TSCTRSTOP = EC_RUN;        // Start Counter   ECap1Regs.ECEINT.bit.CEVT4 = 1;            // 4 events = interrupt}void cap_init(){    EALLOW;    GpioCtrlRegs.GPAPUD.bit.GPIO24 = 0;    // Enable pull-up on cap1 (EPWM1A)    GpioCtrlRegs.GPAMUX2.bit.GPIO24 = 1;   // Configure GPIO0 as cap1复用功能设置，为0代表是普通IO口//  GpioCtrlRegs.GPAPUD.bit.GPIO25 = 0;    // Enable pull-up on GPIO1 (EPWM1B)//  GpioCtrlRegs.GPAMUX1.bit.GPIO25 = 1;   // Configure GPIO1 as EPWM1B    EDIS;    InitECapture();}void All_Init(){    InitSysCtrl();    DINT;    InitPieCtrl();    IER = 0x0000;    IFR = 0x0000;    InitPieVectTable();    EALLOW;    PieVectTable.ECAP1_INT = &ecap1_isr;    EDIS;    Pwm_Init();    cap_init();    IER |= M_INT4;    PieCtrlRegs.PIEIER4.bit.INTx1 = 1;    EINT;    ERTM;}void main(void){    All_Init();    while(1)    {        EPwm1Regs.CMPA.half.CMPA = duty;    }}__interrupt void ecap1_isr(void){   TS1 = ECap1Regs.CAP1;   TS2 = ECap1Regs.CAP2;   TS3 = ECap1Regs.CAP3;   TS4 = ECap1Regs.CAP4;   PEROID = TS3 - TS1;   DUTY1 = TS2 - TS1;   DUTY2 = TS3 - TS2;   initcount++;   ECap1Regs.ECCLR.bit.CEVT4 = 1;   ECap1Regs.ECCLR.bit.INT = 1;   ECap1Regs.ECCTL2.bit.REARM = 1;   PieCtrlRegs.PIEACK.all = PIEACK_GROUP4;}

这里写图片描述
CAP有两个功能，一个是输入捕获，另一个是APWM，即输出PWM波。虽然可以输出PWM，但是我觉得好像没啥用。
在DSP中有一个MOD4寄存器，这个寄存器是不断对数据进行余4，即0-1-2-3-0-1-2-3…….不断的进行循环。比如现在MOD4的值为0，然后基准计数器不断地累加，当捕获到上升沿（或者下降沿，看自己的设定）时，将此时基准计数器的值存入CAP1中，然后MOD4加一，然后当捕获到下一个下降沿时，将此时的基准寄存器的值存入CAP2，然后MOD4加一，依次循环。
这里写图片描述
最后将period = T3 - T1，duty = T2 - T1

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