Photon 2 wake from hibernation by RTC results in WakeUpReason = 0

[cethalon]

Hello!

Is there a way to determine if a photon 2 wakes up via GPIO or RTC from hibernation?

I'm trying to build a program for the Photon 2 that hibernates in one day intervals when external power is not applied.
The Photon 2 can only sleep for ~9 hours at a time. To get around this I was hoping to save the SystemSleepResult wakeupReason to a retained variable that I check in Setup() upon wakeup. Ideally Photon 2 would quickly re-enter hibernation every 9 hours until it's woken up by a GPIO signal.

The issue is that wakeupReason() always returns 0 when I wake from hibernation. Short of adding an external RTC, Is there a workaround for this issue?

Here is a sample code that reproduces the issue I am experiencing.

#include "Particle.h"

SYSTEM_MODE(MANUAL);

SYSTEM_THREAD(ENABLED);

SerialLogHandler logHandler(LOG_LEVEL_INFO);
retained SystemSleepResult result;
retained uint8_t firstwake = 0;
void preSetup() {
  System.enableFeature(FEATURE_RETAINED_MEMORY);
};

STARTUP(preSetup());

void setup() {
  Serial.begin(115200);
  while(!Serial.isConnected());
  Log.info("Start");

  if(!firstwake) firstwake = 1;
  else
  {
    if(result.wakeupReason() == SystemSleepWakeupReason::BY_RTC) Log("Woke up by RTC");
    else if(result.wakeupReason() == SystemSleepWakeupReason::BY_GPIO) Log("Woke up by GPIO");
    else Log("Woke up by unknown reason: %i",result.wakeupReason());
  }
}

void loop() {
  SystemSleepConfiguration hibernateSleepForV4;
  
    hibernateSleepForV4
    .mode(SystemSleepMode::HIBERNATE)
    .gpio(WKP, RISING)
    .gpio(D3, FALLING)
    .duration(5000);

    result =System.sleep(hibernateSleepForV4); 
}

[gusgonnet]

Hi, I imagine you can use resetReason as discussed here and there:

Reset Reasons for P2 and recommended handling

Hey, I see this one when the device wakes up from Hibernate sleep. From what I learned in the community, the Realtek RTL872x on Gen 4 do not have the capability to differentiate between pin and power reset. This is a great question! Let's see what comes out of it.

Determine SoS or Panic reset reason programmatically

Hey Tom, Can you use System.resetReason() and System.resetReasonData() - for after-reset analysis? Example: if (System.resetReason() == RESET_REASON_PANIC) { uint32_t data = System.resetReasonData(); if (data == 8) { // Out of heap memory <your actions> } } you may know this, so please disregard if you do.

Best,

EDIT: Oh I see now, this does not help - sorry

[rickkas7]

I believe the wake reason can't be saved when using HIBERNATE sleep mode on RTL872x devices due to a hardware limitation. The wake reason should work properly in STOP and ULP modes.

[cethalon]

No worries, it's the thought that counts.

[cethalon]

Okay.

I think other developers would benefit from this info being added to the Particle firmware reference.

Thanks for confirming my suspicions,
Cethalon

[gusgonnet]

@cethalon

until it's woken up by a GPIO signal.

Hey, have you figured out a way yet?

If not, one way to detect this could be:

• read the GPIO state very early at boot (using the STARTUP macro?) to see if the GPIO was the cause of reset
• if the GPIO was not it, then it might have been the RTC

This can work only if the GPIO signal is long enough to be detected like this. Otherwise, it will not work.
Best,