topic Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module in S32K

32kHz timer on S32K118 EVB with MCAL Gpt Module

talha_uyar — Tue, 12 May 2020 11:12:22 GMT

Hi,

I am trying to build basic timer application using the Gpt module provided. I am using MCAL 4.3 on S32K118 EVB and using EB tresos and S32DS.

I have set up the McuClockReferencePoint at LPO_CLK_32K and when the frequency is calculated, it is indeed 32000. Then I have set the GptClockReferencePoint_0 to point to this clock, and created a Gpt channel instance named Sample_Timer. EB tresos also calculates the GptChannelTickFrequency as 32000.

However, when I set up my main code to test it, the timer was waaay to fast. So I tried some reasonable large values for overflow. Indeed, when I set the timeout period as 40.000.000 it is overflowing with approximately 2 second intervals.

I am guessing the issue is with the EVB 118 hardware. So even though EB Tresos thinks that there is an oscillator with a frequency of 128Khz, it is not there. I think the only two XTAL's available on EVB are at 8MHz and 40MHz. So I guess I cannot test the LPO functionality with this board?

Is it possible to create a timer with 32 kHz frequency without using prescalers etc.? If so, what am I doing wrong?

Thanks in advance,

M. Talha Uyar

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

namnguyenviet — Mon, 18 May 2020 12:00:09 GMT

Hi talha.uyar@karel.com.tr‌,

These below HW peripherals are available for configure GPT in S32K118: LPIT, FTM, LPTMR and RTC. None of them have LPO_32K as clock source, according to the Reference Manual. So basically, you can't choose LPO_32K as the clock source.

I'd like to clarify a point: These parameters: GptChannelClkSrcRef and GptChannelTickFrequency, as I can see in GPT implementation, only for AUTOSAR compliant, and not to be used at all as an input of GPT clock source. In order to choose clock source, it depends on your GPT HW peripheral (LPIT, FTM, LPTMR, RTC) and clock source to be chosen in MCU peripheral.

In order to create a MCU clock reference point for GPT, it will be more precisely if you choose the corresponding HW peripheral's clock source. For instance, you should choose LPIT_CLK if you choose LPIT as GPT HW peripheral.

Finally, refer this point in the GPT clock reference.

In conclusion, in order to create a 32K clock source for GPT, you might need to use the prescaler, and LPO_32K is unavailable as GPT clock source.

Nam

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

talha_uyar — Wed, 20 May 2020 09:48:08 GMT

Ok, I understand that I cannot use LPO_32K as a clock source for GPT; however, I am stil having isues with the timeout duration of my timer.

I have now configured LPIT as my clock source the clock tick frequency is calculated as 4 MHz, which I guess was expected. However, when I start my timer using Gpt_StartTimer(Sample_Timer, 4000000); the timeout duration is much smaller than 1 second.

I can share the Cfg files for my GPT if you want.

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

namnguyenviet — Wed, 20 May 2020 09:57:39 GMT

Yes, please share me your cfg files (better in .epc - located in output folder also, or .xdm). I'll check in my site if there is anything incorrect.

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

talha_uyar — Wed, 20 May 2020 11:24:22 GMT

Here is the link for Cfg files including .epc files:

https://drive.google.com/open?id=17_VSCVPEIjCyFRWkyomyEVfI0tz8g1GE

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

namnguyenviet — Thu, 21 May 2020 10:01:47 GMT

Hello talha.uyar@karel.com.tr‌,

I tried your configuration and I can succesfully generate a 1 second timeout. Please see my code below. Basically, I call Gpt_StartTimer, then wait until a flag is set in notification. When notification is called, a one-second timeout is finished.

In main function:

Mcu_Init(&McuModuleConfiguration);

Mcu_InitClock(McuClockSettingConfig_0);

/******************************************************************************/
/* GPT */
/******************************************************************************/
Gpt_Init(&GptChannelConfigSet);
Gpt_EnableNotification(Sample_Timer);

/******************************************************************************/
/* PORT */
/******************************************************************************/
Port_Init(&PortConfigSet);

/* Setup all the needed interrupts(and their priorities) */
sys_disableAllInterrupts();

/* Gpt interrupts*/
/* GPT_LPIT_0_CH_0_ISR_USED */
sys_enableIsrSource(20, 0x70);
sys_registerIsrHandler(20, (uint32) & LPIT_0_ISR);

/* Enable external Interrupts */
sys_enableAllInterrupts();

Gpt_StartTimer(Sample_Timer, 4000000);

PTB->PDOR |= (1 << 0);
while (Delay1s_Flag == 0);
PTB->PDOR &= ~(1 << 0);

In notification function:
void Gpt_Timeout_Notification(void)
{
Delay1s_Flag = 1;
}

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

talha_uyar — Thu, 21 May 2020 11:25:21 GMT

I have tried your code and the timeout is definitely not 1 second. I also tried the following code:

Main function:

Mcu_Init(&McuModuleConfiguration);
Mcu_InitClock(McuClockSettingConfig_0);
Mcu_SetMode((Mcu_ModeType)MCU_RUN_MODE);

Port_Init(&PortConfigSet);
UART0_init();
Gpt_Init(&GptChannelConfigSet);

Gpt_EnableNotification(Sample_Timer);
sys_enableIsrSource(LPIT0_Ch0_IRQn, 0x40);
Gpt_StartTimer(Sample_Timer, 4000000);

while(1)
{

}

Notification Function:

void Gpt_Timeout_Notification(void)
{
str = "Hey\r\n";
TransmitData(str, StrLib_StringLen(str));
return;
}

In the terminal, "Hey" is printed much much faster than 1 second.

Can you check if your Mcl configurations are the same as well. Also, I am using S32K118 EVB if that matters.

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

namnguyenviet — Thu, 21 May 2020 12:04:42 GMT

Hello,

LPIT is not depended on MCL HW peripheral at all, so I supposed it's not necessary to check the MCL configuration, also not necessary to call Mcl_Init.

Please check the value in LPIT registers after GPT_StartTimer():

If your registers' value is the same, then it should work, unless the MCU clock generation for LPIT has issue (but I've imported your MCU configuration and it worked)

Nam

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

talha_uyar — Thu, 21 May 2020 12:07:52 GMT

I meant the Mcu configurations, sorry about that. Ok, I will look at the register values.

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

talha_uyar — Thu, 21 May 2020 12:14:02 GMT

Ok TVAL0 -> 0x00030D40 and CVAL0 -> 0x00012629. But my configurations are the same as I posted here.

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

namnguyenviet — Fri, 22 May 2020 06:18:59 GMT

Hello,

Probably the CLK source for LPIT is too much high, leads to CVAL (Counter value) decreases too fast. Please check your PCC and SCG registers:

Best Regards,

Nam

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

talha_uyar — Fri, 22 May 2020 07:32:01 GMT

I think the register values are the same.

I also think this about me using the wrong clock source. When I call the function Gpt_StartTimer(Sample_Timer, 24000000) it overflows at 1 second. This kind of indicates that I am using SYS_CLK instead of SOSCDIV2 which is at 24 MHz instead of 4 MHz. I cannot understand why, though.

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

namnguyenviet — Fri, 22 May 2020 07:38:25 GMT

Hello,

Can you check exact period time the LPIT overflow in case of using SOSC with 4MHz clock source?

Nam

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

talha_uyar — Wed, 27 May 2020 06:30:16 GMT

Ok, I don't exactly know how to measure the exact period without manually timing it. I have changed my timer to Gpt_StartTimer(Sample_Timer, 400000000); and added two breakpoints: one just before I started the timer and the other when the timer overflows. The period is about 20 seconds. So I guess the period of my original Gpt_StartTimer(Sample_Timer, 4000000); is 0.2 seconds.

Again this is not precise considering I have manually measured the time between the timer starts and overflows but it is a very close estimate (definitely between 20 seconds and 21 seconds -> 0.2 seconds to 0.21 seconds for 4 MHz).

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

namnguyenviet — Wed, 27 May 2020 06:57:42 GMT

Hello talha.uyar@karel.com.tr‌,

I have just carefully looked into this thread, and I found the strange thing here:

Muhammet Uyar wrote:
Ok TVAL0 -> 0x00030D40 and CVAL0 -> 0x00012629. But my configurations are the same as I posted here.

After exit GPT_StartTimer, TDVAL0 should be 0x003D0900 (in dec: 4000000), however TDVAL0 is only 0x00030D40 (in dec: 200000) => timer is extremely shorter than it should be. Can you set breakpoint in this line in Gpt_LPit_StartTimer:

REG_WRITE32(LPIT_TVAL_ADDR32((uint32)u8ModuleIdx,(uint32)u8ChannelIdx),u32Value);

and see the exact value was written to TDVAL register?

Nam

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

talha_uyar — Wed, 27 May 2020 07:32:39 GMT

These register values are just after the overflow. Sorry for the mistake, in the previous code I did some stuff in the timeout function. These are measured just after the timer overflow. Still the timer overflows much faster than 1 second.

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

talha_uyar — Wed, 27 May 2020 08:56:06 GMT

I have also checked the TVAL value just after

REG_WRITE32(LPIT_TVAL_ADDR32((uint32)u8ModuleIdx,(uint32)u8ChannelIdx),u32Value);

TVAL0 -> 0x003D0900

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

namnguyenviet — Wed, 27 May 2020 11:50:55 GMT

Hello talha.uyar@karel.com.tr‌,

Till now, honestly I have no idea what cause the issue. All the registers' value seem to be correct. I assumed there is no issue with SW here, probably it comes from HW.

Could you try with SDK driver to see if the issue still happens? I supposed you might need to use LPIT and Clock driver from SDK. If the issue is still same, then probably your HW has problems, otherwise I will re-check MCAL driver to see any gaps or dependences.

Best Regards,

Nam

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

talha_uyar — Wed, 27 May 2020 12:43:05 GMT

I really hoped you wouldn't say this was a hardware issue. I can share the .elf file for my main project so that you can test it in your hardware. If you have S32K118 EVB, this code should change the colour of the RGB LED every at every two seconds (Blue -> Green -> White -> Red). If it is also changing its value at every two seconds in your hardware, then it cannot be a hardware issue, right?

I will also build a sample project from the SDK and test it as you have suggested.

Re: 32kHz timer on S32K118 EVB with MCAL Gpt Module

talha_uyar — Wed, 27 May 2020 12:54:15 GMT

I have built lpit_periodic_interrupt_s32k118 example project and it is working fine. It is overflowing exactly at the expected time. I don't think the issue is with the hardware.

I am almost certain that the associated clock for the LPIT in my project has the frequency of 20 MHz instead of 4 MHz. I have no idea why but this is almost definitely the source of my problems.