S32K118 VLPS Mode Current Consumption Issue with FreeRTOS

Arunpk — Mon, 07 Jul 2025 04:03:54 GMT

Issue Summary:

When entering VLPS before starting the scheduler, the MCU enters sleep as expected and current drops to ~27µA.
When entering VLPS inside a FreeRTOS task, POWER_SYS_SetMode() returns STATUS_SUCCESS, but the MCU does not enter VLPS properly, and current remains ~1.5mA.

Case 1: Before Scheduler (Working) :

power_status = POWER_SYS_SetMode(VLPS, POWER_MANAGER_POLICY_AGREEMENT);

if (power_status == STATUS_SUCCESS)

__asm volatile("nop");

Called before vTaskStartScheduler().
MCU enters VLPS successfully.
Current consumption: ~27µA.
Debugger halts at nop and only proceeds on interrupt (expected behavior).

Case 2: Inside Task (Not Working) :

INT_SYS_DisableIRQ(PORT_IRQn);

INT_SYS_ClearPending(PORT_IRQn);

peripheral_deinit();

INT_SYS_EnableIRQ(PORT_IRQn);

vPortEnterCritical();

sts = POWER_SYS_SetMode(VLPS, POWER_MANAGER_POLICY_AGREEMENT);

vPortExitCritical();

Called inside a FreeRTOS task after suspending other tasks and deinitializing peripherals.
POWER_SYS_SetMode() returns STATUS_SUCCESS .
MCU does not appear to enter VLPS.
Current consumption: ~1.5mA (higher than expected).
With debugger attached, code proceeds beyond POWER_SYS_SetMode() without interrupt (unexpected).

Case 3: Inside Task with SysTick Disabled (Partially Working) :

INT_SYS_DisableIRQ(PORT_IRQn);

INT_SYS_ClearPending(PORT_IRQn);

peripheral_deinit();

INT_SYS_EnableIRQ(PORT_IRQn);

vPortEnterCritical();

S32_SysTick->CSR &= ~(SYSTICK_CSR_ENABLE_MASK); // Disable SysTick

sts = POWER_SYS_SetMode(VLPS, POWER_MANAGER_POLICY_AGREEMENT);

S32_SysTick->CSR |= SYSTICK_CSR_ENABLE_MASK; // Re-enable SysTick

vPortExitCritical();

Disabling SysTick timer before VLPS seems to help.
Debugger halts until interrupt (expected).
However, current consumption is still ~1.5mA (not the expected ~27µA).

My Setup:

MCU: S32K118
SDK : (s32sdk_s32k1xx_rtm_402)
RTOS: FreeRTOS(1.0.0)
Peripherals are deinitialized and unnecessary tasks are suspended before entering VLPS.
Behavior is same with or without debugger.

Questions:

Why does POWER_SYS_SetMode() not put the MCU into VLPS properly when called from a FreeRTOS task?
Are there additional steps required for VLPS under FreeRTOS (e.g., disabling SysTick or configuring interrupt priorities)?
How can I achieve the same low current (~27µA) when entering VLPS from within a task?

Re: S32K118 VLPS Mode Current Consumption Issue with FreeRTOS

Robin_Shen — Tue, 08 Jul 2025 02:03:50 GMT

The Systick is not available in VLPS since the HCLK (CORE_CLK) is gated-off during Deep Sleep.
For good practice, the user should disable it prior to any VLP entry sequence.

I am not familiar with FreeRTOS, did you choose Systick for the scheduler?

I’m sorry to say that we currently do not have resources to support FreeRTOS issues. FreeRTOS is open source and the user is expected to use rather generic FreeRTOS support if needed:
https://www.freertos.org/RTOS-contact-and-support.html
We apologize for any inconvenience.

Best Regards,
Robin
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topic S32K118 VLPS Mode Current Consumption Issue with FreeRTOS in S32K

S32K118 VLPS Mode Current Consumption Issue with FreeRTOS

Re: S32K118 VLPS Mode Current Consumption Issue with FreeRTOS