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i.mx rt1050 Interrupt Jitter

Question asked by Christian Gradl on Aug 11, 2018

Hi

my interrupt (highest priority) jitters when i do a read from a peripheral register.

How can i prevent this? Does this depend on the different Busclocks?

Here my test code.

 

void IRQHandler_128kHz(void)

{

     PWM2->SM[0].STS = 0xFFFF;
     GPIO2->DR_TOGGLE = (1UL << 30);     // Sync Out Signal
}

int main(void)

{

    while (1)

    {

         myvariable = DMA0->TCD[8].CITER_ELINKNO;    // Read from DMA

         // myvariable = GPT1->CNT;                                    // Read from Timer

         // myvariable = LPSPI1->FSR;                                // Read from SPI

    }

}

 

DMA: 90ns

Timer: 268 ns

SPI: 67 ns

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