eCAP

#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10KHZ

Uint32  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;
}

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。



最后将period = T3 - T1，duty = T2 - T1