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SPI DMA delays or misses SYSTICK ISR?

Question asked by s.gd on Jul 10, 2011
Latest reply on Jul 22, 2011 by s.gd
I have SysTick generating an IRQ every 100 usec. With no SPI DMA occurring I see about 881383 isr occurrences in 90 seconds (ideally 900000) if all clocks were perfect.

When I enable fairly active  SPI DMA while running the same test, I only see about 750000 isr occurrence in 90 seconds.  From what I understand, the SysTick timer is only supposed to stop when the system is halted for debug.

So with DMA active, it appears the Systick ISR can get delayed or possibly even missed. Does this seem possible?

-g

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