topic Re: Systick timer problem of KEA8 in Kinetis Microcontrollers

Systick timer problem of KEA8

623619261 — Mon, 27 Jul 2020 15:46:05 GMT

I have a strange problem with kea8.It

My core clock is FEI mode ,48Mhz,and bus clock is 24Mhz.And configure code as below:

ICS_C2 = 0x20;
ICS_C1 = 0x04;
while ((ICS_S & ICS_S_LOCK_MASK) == 0);
SIM_CLKDIV = 0x01100000;
ICS_C2 = 0x00;

I use systick to make a 1ms interrupt.And configure code as below:

/*!Comment:Set the systick timer as 1ms.*/
SYST_RVR = 48000u;

/*!Comment:set systick source clock.*/
SYST_CSR |= (1 << 2);

/*!Comment:Enable systick.*/
SYST_CSR |= (1 << 0);

/*!Comment:Enable interrupt.*/
SYST_CSR |= (1 << 1);

void SysTick_Handler(void)
{

/*!Comment:Catch the first time entering interrupt.*/
GPIOA_PTOR |= (1 << 13u);
}

The GPIO is correctly configured.When I power on the device ,It delay about 120ms to enter the first interrupt handle function "SysTick_Handler".If I use PIT module instead of systick,the delay time will decreace to 20~30ms.

I want to fix the delay time of systick timer?I use other chip like kea64 FEE mode with systick timer will not have this problem,it delay 20~30ms,too.

I want to know the minimal time to initialize clock FEI and FEE mode(KEA8 KEA64) .

Re: Systick timer problem of KEA8

Alexis_A — Wed, 29 Jul 2020 22:16:35 GMT

Hello Chari Zhou,

Let me know if I understand correctly, you're presenting a problem of a delay present in the systick that is not present if you use other timers like the LPIT but this only happens when you use the internal oscillator but with the external one doesn't happen in the KEA64, am I correct?

Does this also happen using the FEE mode in the KEA8 or only with the FEI?

Best Regards,

Alexis Andalon

Re: Systick timer problem of KEA8

623619261 — Thu, 30 Jul 2020 17:15:20 GMT

Hello Alexis，

You understand correctly！But I only find this problem using KEA8 in FEI mode.I think FEE mode works correctly because I did not find the similar problem before.

Best Regards！

Re: Systick timer problem of KEA8

Alexis_A — Fri, 31 Jul 2020 21:12:06 GMT

Hello Charl,

Can you let me know how are you measuring this time? And also, could you try enabling the PIT and the Systick at the same time and check if the same delay appears?

Best Regards,

Alexis Andalon

Re: Systick timer problem of KEA8

623619261 — Fri, 31 Jul 2020 22:01:14 GMT

Hello Alexis，

1. Can you let me know how are you measuring this time?

I do this by measuring the GPIO.I set PTB4 at the end of initialize code and toggle PTB4 in the systick timer interrupt handle function.

2. And also, could you try enabling the PIT and the Systick at the same time and check if the same delay appears?

OK，I will try this on work day.

Best Regards！

Charl

Re: Systick timer problem of KEA8

623619261 — Mon, 03 Aug 2020 02:04:32 GMT

Hello Alexis，

And also, could you try enabling the PIT and the Systick at the same time and check if the same delay appears?

Only the systick timer has this problem！

Best Regards！

Charl

Re: Systick timer problem of KEA8

Alexis_A — Thu, 06 Aug 2020 23:29:28 GMT

Hello Charl,

I tried to replicate this in the TRK-KEA8 but I couldn't do it, in my test the signals are shifted by some microseconds, this is the signals that I capture and as you see there isn't any perceptive delay:

The delay is around 13 us between the two signals:

You can check my code below. This is using the S32 Design Studio IDE.

Best Regards,
Alexis Andalon