Last Will Message - Availability

[smith844]

Is there a simple way to implement a LWT message in the similar way to Tasmota/SONOFF. I have several sonoff devices with Tasmota which give an online/offline message via the LWT which means if a device is out of sync or missing it shows up correctly. I would like to implement this in the code for the lights to allow me to have the correct state in Home Assistant. I have searched a number of threads on the forums but its a bit inconclusive or right at the edge of my knowledge.
Thanks in advance for any help you can give me.

[Joeboyc2]

Hey @smith844 ,
I have some code for this running on another node, i#ll see if i can find the script this evening and upload the sections for you

[smith844]

@Joeboyc2
That is very kind. I should add I have looked at lots of pages of code, the source for pubsubclient and various wiki entries for last will messages but its still a little confusing, I dont want to break the existing code with my efforts

[Joeboyc2]

no worries, here is what you need to do:

Add this line somewhere at the top of the sketch (i added mine under the other topics (line:50ish))
const char* LWT_topic = "tele/topic/LWT"; //name this whatever you want to use

Then replace your reconnect function with this:

void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Attempt to connect
if (client.connect(SENSORNAME, mqtt_username, mqtt_password, LWT_topic, 0, 1, "Offline")) {
Serial.println("connected");
client.subscribe(light_set_topic);
client.publish(LWT_topic, "Online", true);
setColor(0, 0, 0);
sendState();
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}

Then add this to the light section you have in home assistant:
availability_topic: "tele/topic/LWT" //make sure you match this to the one you added to the sketch

[h0jeZvgoxFepBQ2C]

I'm really a noob in arduino programming, would you mind to make a PR @Joeboyc2 ?

[Joeboyc2]

Hey @lichtamberg
I've raised PR's #111 #112 for this