F28035ECAP捕获模块问题-TI中文支持网

ECAP捕获模块配置程序

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 = 0; // Make sure the counter is stopped

// Configure peripheral registers

ECap1Regs.ECCTL2.bit.CONT_ONESHT = 0; // 0:连续模式 1:单次模式

ECap1Regs.ECCTL2.bit.STOP_WRAP = 3; // Stop at 4 events

ECap1Regs.ECCTL1.bit.CAP1POL = 1; // Falling edge

ECap1Regs.ECCTL1.bit.CAP2POL = 1; // Rising edge

ECap1Regs.ECCTL1.bit.CAP3POL = 1; // Falling edge

ECap1Regs.ECCTL1.bit.CAP4POL = 1; // Rising edge

ECap1Regs.ECCTL1.bit.CTRRST1 = 1; // 0：在CAP1捕获后不重置计数；1：在CAP1捕获后重置计数

ECap1Regs.ECCTL1.bit.CTRRST2 = 1; // Difference operation

ECap1Regs.ECCTL1.bit.CTRRST3 = 1; // Difference operation

ECap1Regs.ECCTL1.bit.CTRRST4 = 1; // Difference operation

ECap1Regs.ECCTL2.bit.SYNCI_EN = 0; // Enable sync in：禁止同步信号加载

ECap1Regs.ECCTL2.bit.SYNCO_SEL = 2; // Pass through：10或11：屏蔽同步信号输出

ECap1Regs.ECCTL1.bit.CAPLDEN = 1; // Enable capture units

ECap1Regs.ECCTL2.bit.TSCTRSTOP = 1; // Start Counter 0：计数器停止；1：计数器计数

//ECap1Regs.ECCTL2.bit.REARM = 1; // arm one-shot 单次模式重加载控制

ECap1Regs.ECCTL1.bit.CAPLDEN = 1; // Enable CAP1-CAP4 register loads

//ECap1Regs.ECEINT.bit.CEVT4 = 1; // 4 events = interrupt

//ECap1Regs.ECEINT.bit.CEVT3 = 1;

//ECap1Regs.ECEINT.bit.CEVT2 = 1;

ECap1Regs.ECEINT.bit.CEVT1 = 1;

}

__interrupt void ecap1_isr(void)

{

// Cap input is syc'ed to SYSCLKOUT so there may be

// a +/- 1 cycle variation

//========================================

ECap1_Tst1 = ECap1Regs.CAP1; // Fetch Time-Stamp captured at t1

ECap1_Tst2 = ECap1Regs.CAP2; // Fetch Time-Stamp captured at t2

ECap1_Tst3 = ECap1Regs.CAP3; // Fetch Time-Stamp captured at t3

ECap1_Tst4 = ECap1Regs.CAP4; // Fetch Time-Stamp captured at t4

Period1 = ECap1_Tst1+ECap1_Tst2; // Calculate 1st period

Period2 = ECap1_Tst3-ECap1_Tst4; // Calculate 2nd period

//Period3 = ECap1_Tst3-ECap1_Tst2; // Calculate 3rd perio

Frequency=1/Period1;

ECap1PassCount++;

ECap1Regs.ECCLR.bit.CEVT1 = 1;

//ECap1Regs.ECCLR.bit.CEVT2 = 1;

//ECap1Regs.ECCLR.bit.CEVT3 = 1;

//ECap1Regs.ECCLR.bit.CEVT4 = 1;

ECap1Regs.ECCLR.bit.INT = 1;

//ECap1Regs.ECCTL2.bit.REARM = 1;

// Acknowledge this interrupt to receive more interrupts from group 4

PieCtrlRegs.PIEACK.all = PIEACK_GROUP4;

}

上述程序配置情况：CAP1-4上升沿捕获，捕获后重新计数，使能中断CEVT1

问题：

一、1.F28035系统时钟配置60MHz，捕获信号发生器1Hz方波时，CAP1-4计数值误差很大

2.捕获信号发生器100Hz方波时，CAP1-4计数值烂到炸，应该为600,000

请问，本身就这样还是程序配置的问题？F28035ECAP模块能捕获的方波的最大频率是多少？

二、疑问CAP1-4必须都用，就不能只用一个或两个吗？我刚才试了一下只配置CAP1-2，其他CAP3-4所有配置都屏蔽掉，还是走完四个边沿才进CAP1中断

Jun Zhang10：

好好看完ECAP的部分就能找到答案了，如果找不到再看一遍。