Why watchdog not working with MySensors?

[Dmytro Zadvornov]

Hello,

I faced with the same issue like https://forum.mysensors.org/topic/9946/watchdog-not-watchdogging/1
MySensor ver 2.3.1
Optiboot ver 8.0
atmega328, 8MHz
I have tested two codes on the one board and the result is bellow.
This test code works well. Watchdog is working and Atmega is rebooting.

#include <Arduino.h>
#include <avr/wdt.h>
  
#define STATUS_LED_PIN        A2

void setup() {
  wdt_disable();
  Serial.begin(9600);
  Serial.println("Setup..");
  pinMode(STATUS_LED_PIN, OUTPUT);
  digitalWrite(STATUS_LED_PIN, 0);
  
  Serial.println("Wait 5 sec..");
  delay(5000);
  wdt_enable (WDTO_8S);
  Serial.println("Watchdog enabled.");
}

int timer = 0;

void loop(){
  if(!(millis()%1000)){
    timer++;
    Serial.println(timer);
    digitalWrite(STATUS_LED_PIN, digitalRead(STATUS_LED_PIN)==1?0:1); delay(1);
  }
  //wdt_reset();
}

But this code is not working. Watchdog is not working.

#include <Arduino.h>
#include <avr/wdt.h>
  
// RFM95
  #define MY_RADIO_RFM95
  //#define MY_DEBUG_VERBOSE_RFM95
  #define MY_RFM95_FREQUENCY (RFM95_868MHZ)
  #define MY_RFM95_MODEM_CONFIGRUATION RFM95_BW125CR45SF128

  #define MY_NODE_ID 10
  #define MY_PARENT_NODE_ID 0
  #define MY_PARENT_NODE_IS_STATIC

#include <MySensors.h>

#define STATUS_LED_PIN        A2

void setup() {
  wdt_disable();
  Serial.begin(9600);
  Serial.println("Setup..");
  pinMode(STATUS_LED_PIN, OUTPUT);
  digitalWrite(STATUS_LED_PIN, 0);
  
  Serial.println("Wait 5 sec..");
  delay(5000);
  wdt_enable (WDTO_8S);
  Serial.println("Watchdog enabled.");
}

int timer = 0;

void loop(){
  if(!(millis()%1000)){
    timer++;
    Serial.println(timer);
    digitalWrite(STATUS_LED_PIN, digitalRead(STATUS_LED_PIN)==1?0:1); delay(1);
  }
  //wdt_reset();
}

What I am doing wrong?

[mfalkvidd]

@dmytro-zadvornov MySensors will automatically reset the watchdog every time loop is exited.

[Dmytro Zadvornov]

@mfalkvidd Thx for you answer.
If I understand you right MySensor has implicit call wdt_reset()?
And in this case this new code will reboot.

#include <Arduino.h>
#include <avr/wdt.h>
  
// RFM95
  #define MY_RADIO_RFM95
  //#define MY_DEBUG_VERBOSE_RFM95
  #define MY_RFM95_FREQUENCY (RFM95_868MHZ)
  #define MY_RFM95_MODEM_CONFIGRUATION RFM95_BW125CR45SF128

  #define MY_NODE_ID 10
  #define MY_PARENT_NODE_ID 0
  #define MY_PARENT_NODE_IS_STATIC

#include <MySensors.h>

#define STATUS_LED_PIN        A2

void setup() {
  wdt_disable();
  Serial.begin(9600);
  Serial.println("Setup..");
  pinMode(STATUS_LED_PIN, OUTPUT);
  digitalWrite(STATUS_LED_PIN, 0);
  
  Serial.println("Wait 5 sec..");
  delay(5000);
  wdt_enable (WDTO_8S);
  Serial.println("Watchdog enabled.");
}

int timer = 0;

void loop(){
  if(!(millis()%1000)){
    timer++;
    Serial.println(timer);
    digitalWrite(STATUS_LED_PIN, digitalRead(STATUS_LED_PIN)==1?0:1); delay(1);
  }
  delay(20000);
  //wdt_reset();
}

I will try it later

[mfalkvidd]

@dmytro-zadvornov delay will also reset the watchdog

[Dmytro Zadvornov]

Hi,
I have tried last code, and it works - the watchdog reboot MC. As expected.

@mfalkvidd Why you think delay() should reset the watchdog?

[mfalkvidd]

@dmytro-zadvornov thanks for reporting back.

Sorry for my mistake. I thought most platforms called yield() inside delay(), and yield() usually resets the watchdog. Example https://github.com/arduino/ArduinoCore-avr/blob/b7c607663fecc232e598f2c0acf419ceb0b7078c/cores/arduino/wiring.c#L106
But since your test shows that the watchdog is tripped, the watchdog is not reset inside delay().

https://github.com/arduino/ArduinoCore-avr/blob/b7c607663fecc232e598f2c0acf419ceb0b7078c/cores/arduino/Arduino.h#L38 shows that avr does not reset watchdog in yield().