2394624_en-US

[#1]

MCXA266: WUU wake-up flags are 0 after Deep Power-Down wake-up (SRS=0x4010, SSRS=0x4011)

Hello,

I am investigating WUU wake-up behavior from Deep Power-Down mode on the FRDM-MCXA266 board.

Environment:
- MCU: MCXA266
- Board: FRDM-MCXA266
- SDK Example project: frdmmcxa266_power_mode_switch_ll_mcxa
- SDK version: 26.6.000
- Development environment: MCUXpressoIDE_25.6.136

I added the following code near the beginning of main() to read the reset and wake-up status before BOARD_InitHardware() is called.

/*******************************************************************************
 * Variables
 ******************************************************************************/

char *const g_modeNameArray[] = APP_POWER_MODE_NAME;
char *const g_modeDescArray[] = APP_POWER_MODE_DESC;
uint32_t resetCount;
uint32_t resetStatus;
uint32_t resetStickyStatus;
uint32_t wakeupResource;
uint32_t wuuWakeupPinsFlag;

/*******************************************************************************
 * Code
 ******************************************************************************/

int main(void)
{
    uint32_t freq;
    app_power_mode_t targetPowerMode;
    bool needSetWakeup = false;
    
    // --- START ADDED CODE ---
    resetStatus = CMC_GetSystemResetStatus(CMC);
	resetStickyStatus = CMC_GetStickySystemResetStatus(CMC);
	CMC_ClearStickySystemResetStatus(CMC, resetStickyStatus);
	wakeupResource = CMC_GetWakeupSource(CMC);
	wuuWakeupPinsFlag = WUU_GetExternalWakeUpPinsFlag(WUU0);
	WUU_ClearExternalWakeUpPinsFlag(WUU0, wuuWakeupPinsFlag);
	// --- END ADDED CODE ---
    
	BOARD_InitHardware();
	
	// --- START ADDED CODE ---
    DbgConsole_Printf("CMC_GetSystemResetStatus(CMC) = 0x%x\r\n", resetStatus);
	DbgConsole_Printf("CMC_GetStickySystemResetStatus(CMC) = 0x%x\r\n", resetStickyStatus);
	DbgConsole_Printf("CMC_GetWakeupSource(CMC) = 0x%x\r\n", wakeupResource);
	DbgConsole_Printf("WUU_GetExternalWakeUpPinsFlag(WUU0) = 0x%x\r\n", wuuWakeupPinsFlag);
	// --- END ADDED CODE ---
	APP_SetVBATConfiguration();
    APP_SetSPCConfiguration();
    APP_InitWaketimer();

The complete relevant output is:
```
Normal Boot.

########################### Power Mode Switch Demo ###########################
Core Clock = 240000000Hz
Power mode: Active

Select the desired operation

Press A to enter: Active mode
Press B to enter: Sleep mode
Press C to enter: DeepSleep mode
Press D to enter: PowerDown mode
Press E to enter: DeepPowerDown mode

Waiting for power mode select...

Deep Power Down: The whole VDD_CORE voltage domain is power gated.

Please select wakeup source:
Press A to select TIMER as wakeup source;
Press B to select WAKE-UP-BUTTON as wakeup source;

Waiting for wakeup source select...
Wakeup Button Selected As Wakeup Source.
Please press SW2 to wakeup.
Isolate power domains: VDD_USB.

CMC_GetSystemResetStatus(CMC) = 0x4010
CMC_GetStickySystemResetStatus(CMC) = 0x4011
CMC_GetWakeupSource(CMC) = 0x0
WUU_GetExternalWakeUpPinsFlag(WUU0) = 0x0

Normal Boot.
```

At the initial startup, the following values were printed:

CMC_GetSystemResetStatus(CMC) = 0x110
CMC_GetStickySystemResetStatus(CMC) = 0x110
CMC_GetWakeupSource(CMC) = 0x0
WUU_GetExternalWakeUpPinsFlag(WUU0) = 0x0

I then selected Deep Power-Down mode, selected WAKE-UP-BUTTON as the wake-up source, and pressed SW2.

The MCU successfully woke up, and the application restarted, but the following values were printed:

CMC_GetSystemResetStatus(CMC) = 0x4010
CMC_GetStickySystemResetStatus(CMC) = 0x4011
CMC_GetWakeupSource(CMC) = 0x0
WUU_GetExternalWakeUpPinsFlag(WUU0) = 0x0

My interpretation of the CMC reset status is:

- 0x00004010: Software Reset + Warm Reset
- 0x00004011: Software Reset + Warm Reset + Deep Power-Down Wake-up Reset

If this interpretation is correct, the sticky status appears to indicate that a Deep Power-Down wake-up reset occurred first, followed by a software warm reset.

I checked the application startup code, system_MCXA266.c, and the example sources, but I could not find NVIC_SystemReset(), SYSRESETREQ, or an SCB->AIRCR write.
I also added a counter to SystemInitHook() using a retained NOLOAD variable. SystemInitHook() was executed only once after wake-up, so I could not find evidence of a software reset after SystemInit().

My questions are:

1. Is SRS = 0x4010 and SSRS = 0x4011 expected after a WUU wake-up from Deep Power-Down?
2. Does the MCXA266 Boot ROM or Extended Bootloader issue a software warm reset before the application starts?
3. What is the recommended method for identifying which WUU pin caused the Deep Power-Down wake-up?

My current interpretation of the CMC reset status is as follows, but please correct me if I have misunderstood the bit definitions:
English is not my first language, so please let me know if any part of my explanation is unclear.

Thank you.

MCXARe: MCXA266: WUU wake-up flags are 0 after Deep Power-Down wake-up (SRS=0x4010, SSRS=0x4011)

Hello @ka-2020 

Thanks for your question. I will reproduce the test on my side using the same setup and investigate the behavior. Once I have the results, I will get back to you with my findings and answers to all of your questions.

Thank you for your patience and support.

BR

Alice