Posted on April 22, 2015 at 16:19 Hello!
Once again, I have problems with interrupt priorities (the issue I started with this topic has never been solved).For my current project, Ihave a very high priority ISR which must preempt all other ISRs. I tried different priorities and settings within the source code, butI wasn´t able to get this behavior.
Therefore, I set up a small demo project for SPC56xL Discovery Board (based on SPC56EL OS-Less Demo Application from SPC5 Studio)
Within this application, I integrated two PIT timer interrupts (channel1 and channel2). One interrupt handler gets a high priority (8) and the other one a low priority (2). I expected, that the high priority preempts the lower priority. But the higher priority interrupt is only executed when the lower priority isn´t running.
For better understanding, I attached a picture. In this picture, signal D6 represents the lower prior interrupt, D4 the higher prior interrupt. The two pins are set at the beginning of the corresponding ISR and cleared at the end of ISR.
To be sure that it isn´t a problem with my interrupt handlers, I also created the ISRs using the SPC5 Application Configuration with activated ''Preemptable ISRs'' option. Nevertheless, I got the same result as with my ''own'' interrupt handlers.
These are the interrupt handlers in osal_cfg.c:
/*===========================================================================*/
/* Module ISRs. */
/*===========================================================================*/
/*
* ISR_1 ISR function (vector 61).
*/
OSAL_IRQ_HANDLER(vector61) {
OSAL_IRQ_PROLOGUE();
/* ISR code here.*/
Task_10us();
/* Resets the PIT channel 0 IRQ flag.*/
PIT.CHANNEL[2].TFLG.R = 1;
OSAL_IRQ_EPILOGUE();
}
/*
* ISR_2 ISR function (vector 60).
*/
OSAL_IRQ_HANDLER(vector60) {
OSAL_IRQ_PROLOGUE();
/* ISR code here.*/
Task_100us();
/* Resets the PIT channel 0 IRQ flag.*/
PIT.CHANNEL[1].TFLG.R = 1;
OSAL_IRQ_EPILOGUE();
}
/*===========================================================================*/
/* Module exported functions. */
/*===========================================================================*/
/**
* @brief Generated initialization code.
*
* @special
*/
void osal_cfg_init(void) {
INTC_PSR(OSAL_VECTOR_ISR_1)=INTC_PSR_ENABLE(INTC_PSR_CORE0, 8);
INTC_PSR(OSAL_VECTOR_ISR_2)=INTC_PSR_ENABLE(INTC_PSR_CORE0, 2);
}
/** @} */
Additionally, OSAL_ENABLE_IRQ_PREEMPTION in osal_cfg.h is set TRUE
#if !defined(OSAL_ENABLE_IRQ_PREEMPTION)
#define OSAL_ENABLE_IRQ_PREEMPTION TRUE
#endif
What is the reason for the described behavior? And how I have to configure my system toactivate preemption of lower priorities by higher priority ISRs?
Best regards,
Patrik
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Attachments : scope_72.png :
https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006I0Vk&d=%2Fa%2F0X0000000bZo%2FrJoqsMF2nqhS.6_N.508vRWfiqkn9aZhUOcTRN0gUM4&asPdf=false
