S32KのトピックRe: LPIT Clear Flag

LPIT Clear Flag

Juve75 — Fri, 12 Mar 2021 15:09:31 GMT

Hi to all, I have a question: I'm using a LPIT for a timer and I used the SDK routine(S32 Design Studio for ARM Version 2.2. with micro S32K142)

When I clear the interrupt flag, the timer to do this instruction is very high (30us); I verify this duration using an output pin (See code below) so if I used a 100us timer, the microcontroller works 30% of the time to clear the interrupt flag.

static inline void LPIT_ClearInterruptFlagTimerChannels(LPIT_Type * const base,

uint32_t mask)

{

/* Write 1 to clear the interrupt flag. */

PINS_DRV_WritePin(PTC,9,1); // wood

base->MSR = mask;

PINS_DRV_WritePin(PTC,9,0); // wood

the instruction base->MSR = mask is convert in assembler code as:

284           base->MSR = mask;
00004464:   ldr     r4, [pc, #20]   ; (0x447c <LPIT_DRV_ClearInterruptFlagTimerChannels+40>)
00004466:   str     r6, [r4, #12]

could you help me?

thanks

Re: LPIT Clear Flag

Robin_Shen — Mon, 15 Mar 2021 07:57:28 GMT

Hi Juve75,

The method of flipping IO to measure code execution time is inaccurate.
Please refer: Measure the running time of one function on S32K
These two assembly codes will not take such a long time.

Best Regards,
Robin
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Re: LPIT Clear Flag

Juve75 — Tue, 16 Mar 2021 08:10:33 GMT

Dear Robin,

I know that this kind of IO test is not accurate, but if I simply raise up and down the port, the duration time is 0,5us, not 30us. I also use this test to estimate the duration of other code but without this delay time.

Anyhow I have a look to Measure the running time of one function on S32K that you suggest.

Re: LPIT Clear Flag

Walter99 — Wed, 21 Jul 2021 19:05:09 GMT

Been looking for this: Measure the running time of one function on S32K .

Thanks for sharing. Is there a more detailed article on this topic available here?

Regards