Stop Mode in s32k148

[Vamshi_]

Hi NXP Team,

I’m working on low-power implementation on S32K148 using S32DS 3.5. I have configured a GPIO interrupt (button) such that the MCU should:

1. enter STOP1,

2. wake up on button press, execute a small task, and

3. Return to STOP1 (repeat continuously).

Current measurements (using Nordic Power Profiler Kit 2)

• Sleep (expected STOP1): 16.30 mA (total board)

• Normal run: 43.98 mA (total board)

• PPK2 connections: VDD/VIN connected at J7 (2–3)

What I tried for MCU isolation

• Based on the schematic, I removed the 0 Ω resistor (R59) in the MCU VDD path to isolate the MCU supply.

• However, the MCU still appears to be powered (so isolation is incomplete).

Support needed

1. STOP1 verification:

   • Can you review/confirm whether my current configuration/code is actually entering STOP1?

   • If not, please share the correct sequence/steps to enter STOP modes (STOP1 specifically) and wake up via button interrupt, execute a task, and return to STOP.

2. Wake-up source configuration:

   • For STOP1, what is the recommended/required configuration for GPIO wake-up (PORT interrupt/AWIC/any additional low-power wake configuration)?

3. Correct PPK2 connection point for MCU-only current:

   • Where exactly should I connect PPK2 VDD/VIN so that only the MCU supply is measured (not the full board current)?

   • Which jumpers/links should be removed/changed to fully isolate the MCU supply?

4. Why the MCU still powers after removing R59:

   • What are the possible alternate power paths (VDDA/VDDIO rails, debugger/OpenSDA, protection diode back-powering through I/Os, etc.) on this board, and which components/jumpers/resistors must be removed to prevent that?

If needed, I can share my project configuration and the specific low-power/interrupt setup code sections for review.

[Vamshi_]

In my current implementation, I am requesting STOP mode at runtime from the GPIO interrupt as per my code flow. Can you confirm whether this sequence will actually place the S32K148 into STOP1 mode rather than configuring it in the MEX file and using it?

[danielmartynek]

Hi @Vamshi_ 

Power_Ip_SetMode() will place it in the Stop mode (with WFI).

[danielmartynek]

Hi @Vamshi_,

1.

Do not modify the modeConfig structure at runtime.
The configuration must be done in the .mex file, and Power_Ip_aModeConfigPB[1] should be used when calling Power_Ip_SetMode().

To verify the selected power mode, enable CLKOUT and measure the BUS_CLK frequency on that pin.

2.

Just configure and enable the GPIO interrupt, that is all.

In STOP mode, the NVIC is not active. It is replaced by the AVIC.

3 & 4.

If V_GPIO > VDD + Vf, the MCU can be unintentionally powered through the GPIOs, since all GPIOs are clamped to VDD.
To prevent this, R59 must be removed. However, you must then ensure that the MCU is properly powered through connector J19.

Additionally, keep in mind:

• GPIO outputs driving external loads will increase overall MCU VDD power consumption.
• No GPIO input should be left floating.

Regards,

Daniel

[Vamshi_]

And also can you tell me is it needed to implement the __asm volatile ("WFI"); instruction by ourself in the code after setting the mode in stop1 mode ?

[danielmartynek]

The WFI instruction is already implemented in the RTD driver when you call Power_Ip_SetMode().

[Vamshi_]

Can we not change the mode using the power driver in the runtime?

[danielmartynek]

There is no need to change it in the run time.

The driver generates it as a constant.

You can have many different configurations in the array.

BR, Daniel

[Vamshi_]

In my current implementation, I am requesting STOP mode at runtime from the GPIO interrupt as per my code flow. Can you confirm whether this sequence will actually place the S32K148 into STOP1 mode rather than configuring it in the MEX file and using it?