Could not wake up from sleeping mode

albert_zhou · ‎12-09-2019

I could not get the chip KL27Z64VFM4 wake up from sleeping mode with interrupt. I followed AN4503 power management for Kinetis. When I remove line asm("WFI"); the MCU could not goes into sleep. I don't know what I did wrong?

here is the code:

Initial(); //main clock =2MHz LIRC Bus/flash =500KHz.

Main
{

Process();

Sleep();
}

Void sleep(void)

{

SMC->PMPROT = SMC_PMPROT_AVLP_MASK;

SMC->PMCTRL &= ~SMC_PMCTRL_STOPM_MASK;

SMC->PMCTRL |= SMC_PMCTRL_STOPM(0x2);

SMC->PMCTRL=SMC->PMCTRL;

SCB->SCR |=(1UL << 2U); //SCB_SCR_SLEEPDEEP_MASK;

asm("WFI");

__enable_irq();

}

Robin_Shen · ‎12-11-2019

Hi Albert,

That Application Note use APIs of Kinetis software development kit (SDK). The KSDK is no more recommend for new design.
Please download the latest MCUXpresso SDK.
Then refer the power example in SDK_2.6.0_MKL27Z64xxx4.

Best Regards,

Robin

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albert_zhou · ‎12-11-2019

Hi Robin,

Thanks for your respond to my question. I know the MCUxpressor is newer but my kinetis is holding the old project

I have to use. I just try to add a couple lines of code to get the chip to sleep and wakeup by LPUART1.

Could please help me to solve the problem?

Oh, I did add the line in the initial();

SMC->PMPROT =BIT5+BIT3+BIT1; //42

Albert

mjbcswitzerland · ‎12-11-2019

Hi Albert

Beware that SMC_PROT is a 'write-once' register and so if you set it in initialisation code it can never be changed again (until after a power cycle).
If I interpret your code correctly you are setting VLPS mode. This only allows asynchronous interrupts on the UART so you need to make sure that you enable RxD edge detection for it to be able to wake you.
See also VLPS with continuous UART operation: https://community.nxp.com/message/421247#421247

Regards

Mark

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albert_zhou · ‎12-11-2019

Hi Mark,

Thanks for your response.

Do you mean I need also enable the RX pin with failing edge in order to wake up the VLPS mode? I will try that.

The original code has LPUART1 interrupt working.

Best regards,

Albert Zhou

Sr. Electronics Engineer

Sensorex

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+1 714 230 2768

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mjbcswitzerland · ‎12-11-2019

Yes, in VLPS the UART is not actually working - its clocks are stopped - but it can detect an edge on its RxD line (asynchronous) and wake from that. Whether you miss the data depends on the UART speed, the clock used in RUN mode and the time it takes for the processor to get these ready after waking.