PGA970: SYST_Handler

Hi Paul,

There may be another place where the SYST interrupt needs to be enabled. I will have to look into this. It is likely in the adc config file.

Regards,

Scott

Hi Scott,
i made a programm in purpose of investigation:

//main program
void main(void)
{
   __set_PRIMASK(0);
   __set_FAULTMASK(0);
   __set_PRIMASK(0);
   SYST_Config(0x0000001F,0x00000007);
   int count=0;
   while(1)
   {
       count++;
   }
}

//--------------------------------------startup_ccs.c file---------------------------------------------
int intcount=0;

static void IntDefaultHandler(void)
{
       intcount++;
}

//---------------------------------------pga970_syst.c-----------------------------------------------
int SYSTcounter=0;
interrupt void SYST_Handler(void)
{
   /* Disable System tick  counter */
   SYST_CSR &= ~ST_ENABLE;

   /* Add code here */
   SYSTcounter++;

   /* Enable System tick  counter */
   SYST_CSR |= ST_ENABLE;
}
#endif /* SYST_TESTING */

I enabled the header files and ran the programm without any errors. It has to be run using the "step into" (F5) function in order to see the value of count.
I was hoping that the program wrongly executed the IntDefaultHandler isntead of the SYST_Handler which doesnt seem to be the case. The count value continues on increasing while the Countflag of SYST_CSR is set. Both of the remaining counting variables remain at zero.
I would guess that there is something wrong with the NVIC but to be honest i dont really have a clue right now. Did you achieve any results by now?
regards,
Paul

Hello Scott,
I figured out that I need some case of "Wait for interrupt" or "sleep" for my project is there something like this implemented?

However I still was not able to call the SYST_Handler function automaitcally through the exception. I added the codeline "Interrupt_Config()" to my code above since this was necesary for the exceptions to work. Now I was able to recieve  the value 001111--> F --> 15 in the xPSR register for exception, which should mean that the Syst_Handler is to be executed which still isnt the case.

regards,
Paul

Hi Scott,
Contacting the ARM support i found the ICSR register which is called NVIC_INT_CTRL with the pga970 it has value of 67108879 --> 100000000000000000000001111.

Assuming that the bits 27-31 are 0, it seems like that the SYSTick exception is the only exception pending, but the ISR pending flag is not set so no interrupt will be executed. how do i fix that?
I didnt hear from you for a while now, are you still working on something?

Regards,
Paul

Hi Paul,

So to summarize, the SYST_Handler function is never being called, even though the exception occurs (which you confirmed from the NVIC_INT_CTRL register) and should trigger the interrupt service routine? Are you certain that the interrupt is not being masked somehow through one of the other interrupt control registers?

Regards,
Scott

Hi Scott,
Yes exactly. No Im not certain that the interrupt is not being masked, how do I check that?

Regards,Paul

Hi Paul,

You would have make sure that the interrupt is actually being enabled. As another question, what are all of the interrupts that you currently have enabled?

Regards,

Scott

Hi Scott,
for enabling the interrupt im using this function:

void Interrupt_Config(void)
{
   /* Clear interrupt pending register */
   NVIC_UNPEND0 = 0xFFFFFFFF;

   /* Set priority of NVIC interrupt */
   NVIC_PRI0 = 0x80400000;
   NVIC_PRI1 = 0xC0C0C0C0;

   /*
    * Enable NVIC interrupts
    * NVIC interrupt for external interrupt 1 i.e. TADC is disabled
    */
   NVIC_ENABLE0 = 0xFFFFFFFD;
}

If I understood this code right, the SysTick interrupt should be enabled.  But  so would be all other interrupts so i guess there is my mistake somewhere.Also I set PRIMASK to Zero. I Do not need any other interrupts than SysTick but I do not know how to enable/disable seperate interrupts yet.

Regards,
Paul