Difficulty getting eCAP4 & 5 working on TMS570LC4357 development kit

Hi Charles,

I tested quite a few things here:

If I disable CAP4 interrupts, CAP5 interrupts work just fine. If I input different frequencies, say 40 kHz to CAP5, and 20 kHz to CAP4, only CAP4 gets serviced. If I alternate disabling CAP4 interrupts, servicing CAP5, and then disabling CAP5 interrupts and re-enabling CAP4 interrupts both get serviced however CAP4 will get serviced 2 times for every 1 CAP5 interrupt serviced.

I have not tried masking CAP4 in the VIM module so I will try that.

- Warren

HI Charles,

So ran some tests this morning, it looks to me like the eCAP4 interrupt request flag never gets cleared.. the following code is generated by HalCoGen:

void ecap4Interrupt(void)
{
    uint16 Int_Flag = ecapREG4->ECFLG & ecapREG4->ECEINT;

/* USER CODE BEGIN (8) */
/* USER CODE END */

    /* Clear Events, */
    /* Note : Current Implementation clears multiple all events set
       before this point, User notification function is called with Flags and user must take care of handling */    
    ecapREG4->ECCLR = Int_Flag;
    
    /* Clears the interrupt flag and enables further interrupts to be generated
       if an event flags is set to 1. */
    ecapREG4->ECCLR = 1U;
    
    /* Passing the Interrupt Flag to the user Notification Function */
    ecapNotification(ecapREG4,Int_Flag);

/* USER CODE BEGIN (9) */
/* USER CODE END */

}

When setting the ecapREG4->ECCLR register to the set interrupt flags to clear, the ECCLR register never changes, and the ECFLG register never clears the flags that the ECCLR register should clear.

- Warren

Hi Warren,

  How did you know that the flag is not getting cleared? Are you using the debugger to single step through the code and find that the flag is not cleared after stepping through the code? If this is the case I think the reason is that the eCAP is in a free run mode. When the CPU is halted by the debugger the eCAP continues to run. Since your input comes in at 20kHz, as soon as you clear the flag it is getting set again. The frequency of setting the flag is much faster and frequent than you clearing it while single stepping. 

  I also created a simple test with both eCAP4 and eCAP5 running. However, I use both eCAPs to generate a simple PWM. eCAP4 generates a PWM 5x faster than the eCAP5. I create a global variable in each ISR to count the number of times the ISR is entered. I let it run for a while. I do see the count in eCAP4 to be 5x more than eCAP5. Nonetheless, both eCAP ISRs are entered unlike your original description where you said the eCAP5 ISR was never entered. 

  Please see attached project. 6232.LC4357_eCAP4_eCAP5_interrupt.zip

Charles,

I implemented your example and everything works fine. I incrementally changed it to be exactly like our code. The only difference between your working example, and my non working example is now the printf() statements used in the eCAP example to print the period in ns to the console. Once I removed the printf() statements from my example code mine worked just fine.

Any thoughts as to why printf() broke my example project?

- Warren