RTL872x watchdog does not work during sleep

gusgonnet · February 18, 2025, 2:40am

Hi, I'm trying to configure the hardware watchdog on a muon to reset it in case something goes wrong, but it never resets it.
What am I doing wrong?

Thanks!

source code:

#include "Particle.h"
SYSTEM_MODE(SEMI_AUTOMATIC);

Serial1LogHandler logHandler(115200, LOG_LEVEL_INFO);

void setup()
{
  Watchdog.init(WatchdogConfiguration()
                    .capabilities(WatchdogCap::SLEEP_RUNNING)
                    .timeout(20s));
  Watchdog.start();

  SystemSleepConfiguration config;
  config.mode(SystemSleepMode::HIBERNATE)
      .duration(1h);

  SystemSleepResult result = System.sleep(config);
}

void loop()
{
}

(the values set in my demo code are not realistic, I just want the watchdog to do its job)

rickkas7 · February 18, 2025, 1:54pm

I don't see anything obviously wrong with that code.

Watchdog.init() and Watchdog.start() both return a system error code (0 = success); it might be good to log those to see if either is returning an error code.

gusgonnet · February 18, 2025, 3:37pm

ok, thanks, I added the logs and they indeed return 0.
After that, the watchdog never kicks in.

I tried:

SYSTEM_MODE(AUTOMATIC);
config.mode(SystemSleepMode::STOP)
config.mode(SystemSleepMode::ULTRA_LOW_POWER)
.timeout(20000));
.timeout(20s));

unplugged:

an I2C sensor from the QWIIC connector in case this was causing issues
my serial cable connected to TX/RX on the 40pin connector
the usb cable with which I'm programming it
the only thing powering the board is the original battery

Any other ideas?
Thanks,



0000001126 [hal] INFO: Remove Ethernet interface
0000001128 [net.ifapi] INFO: Netif en2 deleted
0000001157 [sys.power] WARN: Disabled by configuration
0000001172 [system] INFO: Device 99874897378947845879 started
0000001234 [hal] INFO: WiFi KM0 firmware initialization started   result=0 (RAM start=10006000 end=1001a000)
0000001239 [hal] INFO: WiFi KM0 firmware initialization completed result=0 (RAM start=10006000 end=10013fa0 reserved=00005000)
0000001261 [hal] INFO: rltk_wlan_set_netif_info: 0, 94:94:4a:07:15:48
0000001391 [hal] INFO: WiFi on
0000001731 [hal] INFO: WiFi off
0000002352 [system.nm] INFO: State changed: NONE -> DISABLED
0000002374 [comm] INFO: channel inited
0000002380 [app] INFO: Watchdog init result=0
0000002382 [app] INFO: Watchdog start result=0

code with logs:

#include "Particle.h"
SYSTEM_MODE(SEMI_AUTOMATIC);

Serial1LogHandler logHandler(115200, LOG_LEVEL_INFO);

void setup()
{
  bool r;
  r = Watchdog.init(WatchdogConfiguration()
                             .capabilities(WatchdogCap::SLEEP_RUNNING)
                             .timeout(20000));

  Log.info("Watchdog init result=%d", r);

  r = Watchdog.start();
  Log.info("Watchdog start result=%d", r);


  SystemSleepConfiguration config;
  config.mode(SystemSleepMode::HIBERNATE)
      .duration(1h);

  SystemSleepResult result = System.sleep(config);
}

void loop()
{
}

This is on deviceOS 6.3.0

gusgonnet · February 19, 2025, 4:12am

I have tested this on a Photon 2, same results, no watchdog reset.

From this topic it seems clear that on certain sleep modes one can configure the watchdog to keep running on Gen3 devices:

Hardware watchdog in Device OS 5.3.0

It is possible to keep internal watchdog running during STOP or ULP sleep mode on nRF52840-based platforms (Argon, Boron, Tracker, B SoMs, E SoMX):
WatchdogConfiguration().capabilities(WatchdogCap::SLEEP_RUNNING)

However I'm still not able to make it work on Muons or Photon 2's.

PS: I updated the title of this topic to reflect the new findings.

gusgonnet · February 19, 2025, 4:21am

Could it be that the option SLEEP_RUNNING does not work on RTL827x MCUs?
I took out the sleep option to nail things down.

If I use this code:

#include "Particle.h"
SYSTEM_MODE(SEMI_AUTOMATIC);
SerialLogHandler logHandler(LOG_LEVEL_TRACE);

void setup()
{
  waitFor(Serial.isConnected, 5000);
  delay(1000);

  bool r;
  r = Watchdog.init(WatchdogConfiguration()
                        .timeout(20000));
  Log.info("Watchdog init result=%d", r);

  r = Watchdog.start();
  Log.info("Watchdog start result=%d", r);

}

void loop()
{
}

The device resets after 20 seconds. This is fantastic.

As soon as I add:

.capabilities(WatchdogCap::SLEEP_RUNNING)

The device never resets, so I do not see the watchdog working even when the device is awake.

I'm currently using DeviceOS 6.3.0, but tried 5.3 quickly, where the feature came out, and there I was still not able to make this work.

Where could the problem be?
Thanks

rickkas7 · February 19, 2025, 8:43am

Since the RTL872x does not support stopping the watchdog in sleep, SLEEP_RUNNING is always true and can't be turned off.

When I briefly looked yesterday I didn't see any obvious check where that would have caused a failure, but it is quite possible that you can't set it.

peekay123 · February 19, 2025, 2:17pm

@rickkas7, the Muon has an onboard AM1805 RTC/Watchdog. I know that DeviceOS will use it for the RTC if found but does it also defer watchdog functionality from the built-in HW watchdog to the AM1805?

rickkas7 · February 19, 2025, 2:27pm

Device OS only uses the AM1805 RTC when HAL_PLATFORM_EXTERNAL_RTC is defined for the platform, and it's only defined for Tracker SoM. This is presumably because Muon and M-SoM are a single platform, and the M-SoM doesn't have a AM1805. So none of the features of the AM1805 are built into Device OS for Muon.

gusgonnet · February 19, 2025, 2:35pm

Alright, let's set aside SLEEP_RUNNING for now.

Has there been any update on why the watchdog isn’t waking up a Photon 2 or a Muon after 20 seconds when they hibernate?

#include "Particle.h"
SYSTEM_MODE(SEMI_AUTOMATIC);
SerialLogHandler logHandler(LOG_LEVEL_TRACE);

void setup()
{
  waitFor(Serial.isConnected, 5000);
  delay(1000);

  bool r;
  r = Watchdog.init(WatchdogConfiguration()
                        .timeout(20000));
  Log.info("Watchdog init result=%d", r);

  r = Watchdog.start();
  Log.info("Watchdog start result=%d", r);

  SystemSleepConfiguration config;
  config.mode(SystemSleepMode::HIBERNATE)
      .duration(1h);

  SystemSleepResult result = System.sleep(config);
}

void loop()
{
}

Thanks!

rickkas7 · February 19, 2025, 4:34pm

That should work; I think engineering will need to investigate.

gusgonnet · February 19, 2025, 6:32pm

ok that sounds promising, are you raising this to their attention or should I?
Thanks again.

gusgonnet · February 19, 2025, 6:33pm

Hey Paul, how do you know this? I thought we needed the RK library for using the onboard ab1805.
Thanks

peekay123 · February 19, 2025, 6:49pm

@gusgonnet, as @rickkas7 pointed out, the RTC portion of the AM1805 is only used by DeviceOS if the device is a Tracker SoM. There is no guarantee that an MSoM will have an AM1805 so it doesn't kick in on the Muon. I wish there was a way, like the PMIC to specify in user code that an AM1805 is present, for any device (that can run newer versions of DeviceOS).

gusgonnet · February 25, 2025, 8:48pm

Hey, just following up in case this got forgotten.
Any news please let me know.
Thanks

rickkas7 · February 25, 2025, 9:03pm

The watchdog on RTL872x does not appear to run in sleep mode, but the Realtek documentation indicates that it should. This is being followed up with Realtek.

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