precise blocking timer in S32K3

JoDo — Wed, 13 Oct 2021 12:30:41 GMT

Hi,

I would like to implement a precise blocking timer that can also be set for a delay of 1us. I am using the code written for the S32K1 MCU and have transferred it to the S32K3 MCU. Unfortunately it does not work properly and I measured about 389us for 1ms (expected time).

Maybe I have chosen the wrong clock source (Core_CLK) or the code is 1:1 transferable for the S32K3.

If someone has a tip for this problem or maybe a better way to implement a blocking timer, that would be great.

#define WAIT_FOR_MUL4_CYCLES(cycles) \ __asm( \ "movs r0, %[cycles] \n" \ "0: \n" \ "subs r0, r0, #4 \n" \ "nop \n\t" \ "bne 0b \n" \ : \ : [cycles] "r" (cycles) \ : "r0", "r1", "cc" \ ) void BCC_MCU_WaitMs(uint16_t delay) { g_sysClk = Clock_Ip_GetClockFrequency(CORE_CLK); uint32_t cycles = (uint32_t) g_sysClk / 1000; /* Advance to next multiple of 4. Value 0x04U ensures that the number * is not zero. */ cycles = (cycles & 0xFFFFFFFCU) | 0x04U; for (; delay > 0U; delay--) { BCC_WAIT_FOR_MUL4_CYCLES(cycles); } } int main(void){ uint8 tggGPIO = 0u; while(1){ Siul2_Dio_Ip_WritePin( GPIO_BlINKY_PORT, GPIO_BlINKY_PIN, tggGPIO); tggGPIO ^= 0x01; WaitMs(1); // approx 389us //WaitMs(2); // approx 760us } }

Re: precise blocking timer in S32K3

danielmartynek — Fri, 15 Oct 2021 14:20:26 GMT

Hi @JoDo,

The S32K3 has a different core.

Why don't use Systick?

You can use the OSIF RTD driver.

BR, Daniel

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precise blocking timer in S32K3

Re: precise blocking timer in S32K3