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Add an external watchdog module #1446

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c89a0e9
Add an external watchdog module
Quency-D Jan 22, 2026
9f38835
Merge pull request #1 from meshcore-dev/dev
Quency-D Jan 22, 2026
9df34e0
Merge branch 'dev' into solar-watchdog
Quency-D Feb 9, 2026
53ff4ed
Fix watchdog code in repeater
Quency-D Feb 9, 2026
1ab8a6f
Address review comments
weebl2000 Mar 4, 2026
f9b830b
Merge pull request #4 from weebl2000/solar-watchdog
Quency-D Mar 4, 2026
7e0d9f6
Merge pull request #10 from meshcore-dev/dev
Quency-D Apr 27, 2026
363ac44
Fix external watchdog timing around sleep
Quency-D Apr 27, 2026
ec9fe67
Merge branch 'dev' into solar-watchdog
Quency-D May 9, 2026
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7 changes: 7 additions & 0 deletions examples/companion_radio/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -110,6 +110,10 @@ void setup() {

board.begin();

#ifdef HAS_EXTERNAL_WATCHDOG
external_watchdog.begin();
#endif

#ifdef DISPLAY_CLASS
DisplayDriver* disp = NULL;
if (display.begin()) {
Expand Down Expand Up @@ -229,4 +233,7 @@ void loop() {
ui_task.loop();
#endif
rtc_clock.tick();
#ifdef HAS_EXTERNAL_WATCHDOG
external_watchdog.loop();
#endif
}
25 changes: 22 additions & 3 deletions examples/simple_repeater/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,10 @@ void setup() {

board.begin();

#ifdef HAS_EXTERNAL_WATCHDOG
external_watchdog.begin();
#endif

#if defined(MESH_DEBUG) && defined(NRF52_PLATFORM)
// give some extra time for serial to settle so
// boot debug messages can be seen on terminal
Expand Down Expand Up @@ -154,17 +158,32 @@ void loop() {
#endif
rtc_clock.tick();

#ifdef HAS_EXTERNAL_WATCHDOG
external_watchdog.loop();
#endif
if (the_mesh.getNodePrefs()->powersaving_enabled && !the_mesh.hasPendingWork()) {
#if defined(NRF52_PLATFORM)
#if defined(NRF52_PLATFORM)
#ifdef HAS_EXTERNAL_WATCHDOG
external_watchdog.feed();
uint32_t sleep_interval = external_watchdog.getIntervalMs() / 1000;
board.sleep((sleep_interval > 1800) ? 1800 : sleep_interval); // nrf ignores seconds param, sleeps whenever possible
#else
board.sleep(1800); // nrf ignores seconds param, sleeps whenever possible
#else
#endif
#else
if (the_mesh.millisHasNowPassed(lastActive + nextSleepinSecs * 1000)) { // To check if it is time to sleep
#ifdef HAS_EXTERNAL_WATCHDOG
external_watchdog.feed();
uint32_t sleep_interval = external_watchdog.getIntervalMs() / 1000;
board.sleep((sleep_interval > 1800) ? 1800 : sleep_interval); // To sleep. Wake up after 30 minutes or when receiving a LoRa packet
#else
board.sleep(1800); // To sleep. Wake up after 30 minutes or when receiving a LoRa packet
#endif
lastActive = millis();
nextSleepinSecs = 5; // Default: To work for 5s and sleep again
} else {
nextSleepinSecs += 5; // When there is pending work, to work another 5s
}
#endif
#endif
}
}
7 changes: 7 additions & 0 deletions examples/simple_room_server/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,10 @@ void setup() {

board.begin();

#ifdef HAS_EXTERNAL_WATCHDOG
external_watchdog.begin();
#endif

#ifdef DISPLAY_CLASS
if (display.begin()) {
display.startFrame();
Expand Down Expand Up @@ -113,4 +117,7 @@ void loop() {
ui_task.loop();
#endif
rtc_clock.tick();
#ifdef HAS_EXTERNAL_WATCHDOG
external_watchdog.loop();
#endif
}
7 changes: 7 additions & 0 deletions examples/simple_secure_chat/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -560,6 +560,10 @@ void setup() {

board.begin();

#ifdef HAS_EXTERNAL_WATCHDOG
external_watchdog.begin();
#endif

if (!radio_init()) { halt(); }

fast_rng.begin(radio_driver.getRngSeed());
Expand Down Expand Up @@ -591,4 +595,7 @@ void setup() {
void loop() {
the_mesh.loop();
rtc_clock.tick();
#ifdef HAS_EXTERNAL_WATCHDOG
external_watchdog.loop();
#endif
}
7 changes: 7 additions & 0 deletions examples/simple_sensor/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,10 @@ void setup() {

board.begin();

#ifdef HAS_EXTERNAL_WATCHDOG
external_watchdog.begin();
#endif

#ifdef DISPLAY_CLASS
if (display.begin()) {
display.startFrame();
Expand Down Expand Up @@ -147,4 +151,7 @@ void loop() {
ui_task.loop();
#endif
rtc_clock.tick();
#ifdef HAS_EXTERNAL_WATCHDOG
external_watchdog.loop();
#endif
}
12 changes: 12 additions & 0 deletions src/helpers/ExternalWatchdogManager.h
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
#pragma once

class ExternalWatchdogManager {
protected:
unsigned long last_feed_watchdog;
public:
ExternalWatchdogManager() { last_feed_watchdog = 0; }
virtual bool begin() { return false; }
virtual void loop() { }
virtual unsigned long getIntervalMs() const { return 0; }
virtual void feed() { }
};
5 changes: 5 additions & 0 deletions variants/heltec_mesh_solar/platformio.ini
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,11 @@ build_flags = ${nrf52_base.build_flags}
-D LORA_TX_POWER=22
-D SX126X_CURRENT_LIMIT=140
-D SX126X_RX_BOOSTED_GAIN=1
-D HAS_EXTERNAL_WATCHDOG
-D EXTERNAL_WATCHDOG_DONE_PIN=9
-D EXTERNAL_WATCHDOG_WAKE_PIN=10
-D EXTERNAL_WATCHDOG_FEED_INTERVAL_MS=480000 ; 8 minute feed interval, safely inside the hardware watchdog timeout

build_src_filter = ${nrf52_base.build_src_filter}
+<helpers/*.cpp>
+<../variants/heltec_mesh_solar>
Expand Down
32 changes: 32 additions & 0 deletions variants/heltec_mesh_solar/target.cpp
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Expand Up @@ -13,6 +13,7 @@ VolatileRTCClock fallback_clock;
AutoDiscoverRTCClock rtc_clock(fallback_clock);
MicroNMEALocationProvider nmea = MicroNMEALocationProvider(Serial1, &rtc_clock);
SolarSensorManager sensors = SolarSensorManager(nmea);
SolarExternalWatchdog external_watchdog;

#ifdef DISPLAY_CLASS
DISPLAY_CLASS display;
Expand Down Expand Up @@ -106,3 +107,34 @@ bool SolarSensorManager::setSettingValue(const char* name, const char* value) {
}
return false; // not supported
}

bool SolarExternalWatchdog::begin() {
last_feed_watchdog = 0;
pinMode(EXTERNAL_WATCHDOG_WAKE_PIN, INPUT);
pinMode(EXTERNAL_WATCHDOG_DONE_PIN, OUTPUT);
delay(1);
digitalWrite(EXTERNAL_WATCHDOG_DONE_PIN, LOW);
delay(1);
feed();
return true;
}
void SolarExternalWatchdog::loop() {
if (millis() - last_feed_watchdog >= EXTERNAL_WATCHDOG_FEED_INTERVAL_MS) {
feed();
}
}

unsigned long SolarExternalWatchdog::getIntervalMs() const {
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@ripplebiz ripplebiz Apr 26, 2026

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If I'm reading this right, this is the remaining time left until next feed() ?
Or should this be whatever the fixed interval is?

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@Quency-D Quency-D Apr 27, 2026

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This is the time remaining until the next feed(), not a fixed time interval.

unsigned long elapsed_ms = millis() - last_feed_watchdog;
if (elapsed_ms >= EXTERNAL_WATCHDOG_FEED_INTERVAL_MS) {
return 0;
}
return EXTERNAL_WATCHDOG_FEED_INTERVAL_MS - elapsed_ms;
}

void SolarExternalWatchdog::feed() {
digitalWrite(EXTERNAL_WATCHDOG_DONE_PIN, HIGH);
delay(1);
digitalWrite(EXTERNAL_WATCHDOG_DONE_PIN, LOW);
last_feed_watchdog = millis();
}
11 changes: 11 additions & 0 deletions variants/heltec_mesh_solar/target.h
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@
#include <helpers/AutoDiscoverRTCClock.h>
#include <helpers/SensorManager.h>
#include <helpers/sensors/LocationProvider.h>
#include <helpers/ExternalWatchdogManager.h>
#ifdef DISPLAY_CLASS
#include <helpers/ui/ST7789Display.h>
#endif
Expand All @@ -30,10 +31,20 @@ class SolarSensorManager : public SensorManager {
bool setSettingValue(const char* name, const char* value) override;
};

class SolarExternalWatchdog : public ExternalWatchdogManager {
public:
SolarExternalWatchdog() {}
bool begin() override;
void loop() override;
unsigned long getIntervalMs() const override;
void feed() override;
};

extern MeshSolarBoard board;
extern WRAPPER_CLASS radio_driver;
extern AutoDiscoverRTCClock rtc_clock;
extern SolarSensorManager sensors;
extern SolarExternalWatchdog external_watchdog;

#ifdef DISPLAY_CLASS
extern DISPLAY_CLASS display;
Expand Down
4 changes: 2 additions & 2 deletions variants/heltec_mesh_solar/variant.h
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Expand Up @@ -34,8 +34,8 @@
#define PIN_SERIAL1_RX (37)
#define PIN_SERIAL1_TX (39)

#define PIN_SERIAL2_RX (9)
#define PIN_SERIAL2_TX (10)
#define PIN_SERIAL2_RX (-1)
#define PIN_SERIAL2_TX (-1)

////////////////////////////////////////////////////////////////////////////////
// I2C pin definition
Expand Down