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| /* =================================================================== | |
| SAMPLE CODE Segments for Home Assistant MQTT Discovery | |
| This is NOT complete code but shows an example of generating a unique ID | |
| for topic/entity publishing based on the device MAC address. | |
| It also includes sample code for creating a Home Assistant device with four | |
| entities via MQTT Discovery, as shown here: | |
| Video: https://youtu.be/VHiCtZqllU8 | |
| Blog: https://resinchemtech.blogspot.com/2023/12/mqtt-auto-discovery.html | |
| It is highly recommended that you include some sort of end-user accessible setting to | |
| enable/disable Home Assistant discovery as some users may not want your device auto-discovered | |
| and Home Assistant currently doesn't provide any prompting... devices/entities are immediately | |
| added as soon as a valid topic/payload are received. | |
| THIS IS AN INCOMPLETE EXAMPLE ONLY!!!! | |
| ===================================================================== */ | |
| //Partial list of libaries - also need Wifi, ESP8266/ESP32 libraries, etc. | |
| #include <PubSubClient.h> | |
| #include <ArduinoJson.h> | |
| #include <ESP8266WebServer.h> //Used for HTTP callback to enable/disable discovery | |
| //Auto-discover enable/disable option | |
| bool auto_discovery = false; //default to false and provide end-user interface to allow toggling | |
| //Variables for creating unique entity IDs and topics | |
| byte macAddr[6]; //Device MAC address | |
| char uidPrefix[] = "rctdev"; //Prefix for unique ID generation (limit to 20 chars) | |
| char devUniqueID[30]; //Generated Unique ID for this device (uidPrefix + last 6 MAC characters) | |
| // ===================================== | |
| // Create Unique ID for topics/entities | |
| // ===================================== | |
| void createDiscoveryUniqueID() { | |
| //Generate UniqueID from uidPrefix + last 6 chars of device MAC address | |
| //This should insure that even multiple devices installed in same HA instance are unique | |
| strcpy(devUniqueID, uidPrefix); | |
| int preSizeBytes = sizeof(uidPrefix); | |
| int preSizeElements = (sizeof(uidPrefix) / sizeof(uidPrefix[0])); | |
| //Now add last 6 chars from MAC address (these are 'reversed' in the array) | |
| int j = 0; | |
| for (int i = 2; i >= 0; i--) { | |
| sprintf(&devUniqueID[(preSizeBytes - 1) + (j)], "%02X", macAddr[i]); //preSizeBytes indicates num of bytes in prefix - null terminator, plus 2 (j) bytes for each hex segment of MAC | |
| j = j + 2; | |
| } | |
| // End result is a unique ID for this device (e.g. rctdevE350CA) | |
| Serial.print("Unique ID: "); | |
| Serial.println(devUniqueID); | |
| } | |
| // =============================== | |
| // Main HA MQTT Discover Function | |
| // This creates a single fictional device with four entities: | |
| // - A dimmer switch with light level, temperature and IP address | |
| // =============================== | |
| void haDiscovery() { | |
| char topic[128]; | |
| if (auto_discovery) { | |
| char buffer1[512]; | |
| char buffer2[512]; | |
| char buffer3[512]; | |
| char buffer4[512]; | |
| char uid[128]; | |
| DynamicJsonDocument doc(512); | |
| doc.clear(); | |
| Serial.println("Discovering new devices..."); | |
| Serial.println("Adding light switch..."); | |
| //Create unique topic based on devUniqueID | |
| strcpy(topic, "homeassistant/light/"); | |
| strcat(topic, devUniqueID); | |
| strcat(topic, "S/config"); | |
| //Create unique_id based on devUniqueID | |
| strcpy(uid, devUniqueID); | |
| strcat(uid, "S"); | |
| //Create JSON payload per HA documentation | |
| doc["name"] = "My MQTT Light"; | |
| doc["obj_id"] = "mqtt_light"; | |
| doc["uniq_id"] = uid; | |
| doc["stat_t"] = "stat/mydevice/switch"; | |
| doc["cmd_t"] = "cmnd/mydevice/switch"; | |
| doc["brightness"] = "true"; | |
| doc["bri_scl"] = "100"; | |
| doc["bri_stat_t"] = "stat/mydevice/brightness"; | |
| doc["bri_cmd_t"] = "cmnd/mydevice/brightness"; | |
| JsonObject device = doc.createNestedObject("device"); | |
| device["ids"] = "mymqttdevice01"; | |
| device["name"] = "My MQTT Device"; | |
| device["mf"] = "Resinchem Tech"; | |
| device["mdl"] = "ESP8266"; | |
| device["sw"] = "1.24"; | |
| device["hw"] = "0.45"; | |
| device["cu"] = "http://192.168.1.226/config"; //web interface for device, with discovery toggle | |
| serializeJson(doc, buffer1); | |
| //Publish discovery topic and payload (with retained flag) | |
| client.publish(topic, buffer1, true); | |
| //Lux Sensor | |
| Serial.println("Adding light sensor..."); | |
| //Create unique Topic based on devUniqueID | |
| strcpy(topic, "homeassistant/sensor/"); | |
| strcat(topic, devUniqueID); | |
| strcat(topic, "L/config"); | |
| //Create unique_id based on decUniqueID | |
| strcpy(uid, devUniqueID); | |
| strcat(uid, "L"); | |
| //Create JSON payload per HA documentation | |
| doc.clear(); | |
| doc["name"] = "Light Level"; | |
| doc["obj_id"] = "mqtt_light_level"; | |
| doc["dev_cla"] = "illuminance"; | |
| doc["uniq_id"] = uid; | |
| doc["stat_t"] = "stat/mydevice/lightlevel"; | |
| doc["unit_of_meas"] = "lx"; | |
| JsonObject deviceS = doc.createNestedObject("device"); | |
| deviceS["ids"] = "mymqttdevice01"; | |
| deviceS["name"] = "My MQTT Device"; | |
| serializeJson(doc, buffer2); | |
| //Publish discovery topic and payload (with retained flag) | |
| client.publish(topic, buffer2, true); | |
| //Temperature Sensor | |
| Serial.println("Adding Temp Sensor..."); | |
| //Create unique Topic based on devUniqueID | |
| strcpy(topic, "homeassistant/sensor/"); | |
| strcat(topic, devUniqueID); | |
| strcat(topic, "T/config"); | |
| //Create unique_id based on decUniqueID | |
| strcpy(uid, devUniqueID); | |
| strcat(uid, "T"); | |
| //Create JSON payload per HA documentation | |
| doc.clear(); | |
| doc["name"] = "Temperature"; | |
| doc["obj_id"] = "mqtt_temperature"; | |
| doc["deve_cla"] = "temperature"; | |
| doc["uniq_id"] = uid; | |
| doc["stat_t"] = "stat/mydevice/temperature"; | |
| doc["unit_of_meas"] = "°F"; | |
| JsonObject deviceT = doc.createNestedObject("device"); | |
| deviceT["ids"] = "mymqttdevice01"; | |
| deviceT["name"] = "My MQTT Device"; | |
| serializeJson(doc, buffer3); | |
| //Publish discovery topic and payload (with retained flag) | |
| client.publish(topic, buffer3, true); | |
| //IP Address Diagnostic | |
| Serial.println("Adding IP Diagnostic Sensor..."); | |
| //Create unique Topic based on devUniqueID | |
| strcpy(topic, "homeassistant/sensor/"); | |
| strcat(topic, devUniqueID); | |
| strcat(topic, "I/config"); | |
| //Create unique_id based on decUniqueID | |
| strcpy(uid, devUniqueID); | |
| strcat(uid, "I"); | |
| //Create JSON payload per HA documentation | |
| doc.clear(); | |
| doc["name"] = "IP Address"; | |
| doc["uniq_id"] = uid; | |
| doc["ent_cat"] = "diagnostic"; | |
| doc["stat_t"] = "stat/mydevice/ipaddress"; | |
| JsonObject deviceI = doc.createNestedObject("device"); | |
| deviceI = doc.createNestedObject("device"); | |
| deviceI["ids"] = "mymqttdevice01"; | |
| deviceI["name"] = "My MQTT Device"; | |
| serializeJson(doc, buffer4); | |
| //Publish discovery topic and payload (with retained flag) | |
| client.publish(topic, buffer4, true); | |
| Serial.println("All devices added!"); | |
| } else { | |
| //Remove all entities by publishing empty payloads | |
| //Must use original topic, so recreate from original Unique ID | |
| //This will immediately remove/delete the device/entities from HA | |
| Serial.println("Removing discovered devices..."); | |
| //Lux Sensor | |
| strcpy(topic, "homeassistant/sensor/"); | |
| strcat(topic, devUniqueID); | |
| strcat(topic, "L/config"); | |
| client.publish(topic, ""); | |
| //Temperature Sensor | |
| strcpy(topic, "homeassistant/sensor/"); | |
| strcat(topic, devUniqueID); | |
| strcat(topic, "T/config"); | |
| client.publish(topic, ""); | |
| //IP Address Sensor | |
| strcpy(topic, "homeassistant/sensor/"); | |
| strcat(topic, devUniqueID); | |
| strcat(topic, "I/config"); | |
| client.publish(topic, ""); | |
| //Light (switch) | |
| strcpy(topic, "homeassistant/light/"); | |
| strcat(topic, devUniqueID); | |
| strcat(topic, "S/config"); | |
| client.publish(topic, ""); | |
| Serial.println("Devices Removed..."); | |
| } | |
| } | |
| // ===================== | |
| // MAIN SETUP | |
| // ===================== | |
| void Setup() { | |
| // The following should be included in (or called from) the main setup routine | |
| //Get MAC address when joining wifi and place into char array | |
| WiFi.macAddress(macAddr); | |
| //Call routing (or embed here) to create initial Unique ID | |
| createDiscoveryUniqueID(); | |
| //Handle web callbacks for enabling or disabling discovery (using this method is just one of many ways to do this) | |
| server.on("/discovery_on",[]() { | |
| server.send(200, "text/html", "<h1>Discovery ON...<h1><h3>Home Assistant MQTT Discovery enabled</h3>"); | |
| delay(200); | |
| auto_discovery = true; | |
| haDiscovery(); | |
| }); | |
| server.on("/discovery_off",[]() { | |
| server.send(200, "text/html", "<h1>Discovery OFF...<h1><h3>Home Assistant MQTT Discovery disabled. Previous entities removed.</h3>"); | |
| delay(200); | |
| auto_discovery = false; | |
| haDiscovery(); | |
| }); | |
| server.begin(); | |
| } |
ah figured it out
Your code has:
serializeJson(doc, buffer1);
//Publish discovery topic and payload (with retained flag)
client.publish(topic, buffer1, true);
serializeJson(doc, buffer2);
//Publish discovery topic and payload (with retained flag)
client.publish(topic, buffer1, true);
serializeJson(doc, buffer3);
//Publish discovery topic and payload (with retained flag)
client.publish(topic, buffer1, true);
serializeJson(doc, buffer4);
//Publish discovery topic and payload (with retained flag)
client.publish(topic, buffer1, true);
I assumed this means the buffer1 was important given it needed to be used as it was nested, appears this is just a typo from a copy paste potentially and should be
serializeJson(doc, buffer1);
//Publish discovery topic and payload (with retained flag)
client.publish(topic, buffer1, true);
serializeJson(doc, buffer2);
//Publish discovery topic and payload (with retained flag)
client.publish(topic, buffer2, true);
serializeJson(doc, buffer3);
//Publish discovery topic and payload (with retained flag)
client.publish(topic, buffer3, true);
serializeJson(doc, buffer4);
//Publish discovery topic and payload (with retained flag)
client.publish(topic, buffer4, true);
You are 100% correct and it was my mistake with my copy and paste from my actual code. I've corrected the gist to show the proper buffers for the publish statements. Sorry for the error, but I appreciate you pointing it out.
Don’t apologise! I learnt a lot from your video and this code, and so much so I didn’t think your code was wrong in any way but after 3 days of wrecking my brain I just analysed step by step and went on a whim.
I know you’re probably less likely to share your codes from projects as they may be very specific, but would be great to see some more of your examples or a write up on a project you’ve done as it’d help bridge the gap between the knowledge gap.
I hope none of this comes across ungrateful, super thankful for your videos and posts, and your prompt response!
Reason I ask is, I seem to be having trouble publishing values to the sensors I created, sometimes seeing a larger code example in full helps identify where we go wrong, you're extremely helpful and knowledgeable and some of your projects you have done are just amazing.
I assumed I needed to do something like:
const char* mqtt_pub_topic_IP = "homeassistant/sensor/TDSMonitorIP";
//IP Address Diagnostic
Serial.println("Adding IP Diagnostic Sensor...");
//Create unique Topic based on devUniqueID
strcpy(topic, "homeassistant/sensor/");
strcat(topic, "TDSMonitor");
strcat(topic, "IP/config");
//Create unique_id based on decUniqueID
strcpy(uid, "TDSMonitor");
strcat(uid, "IP");
//Create JSON payload per HA documentation
doc.clear();
doc["name"] = "IP Address";
doc["uniq_id"] = uid;
doc["ent_cat"] = "diagnostic";
doc["stat_t"] = "stat/TDSMonitor/ipaddress";
JsonObject deviceIP = doc.createNestedObject("device");
deviceIP = doc.createNestedObject("device");
deviceIP["ids"] = "tdsmonitor";
deviceIP["name"] = "TDS Monitor";
serializeJson(doc, buffer4);
//Publish discovery topic and payload (with retained flag)
client.publish(topic, buffer4, true);
client.publish(mqtt_pub_topic_IP, "10.0.0.14");
Note, I tried WiFi.localIP instead of a string with the IP, that didnt work either but I imagine that is because I am doing something that the language doesnt allow, so used a string to keep it simple but when I do it breaks the auto-discovery (as i write this, it could be because the publish above is in the loop or in a step prior to discovery being turned on, will continue to test but hoping you might have something you can share.
First, I believe you are publishing the IP address to the wrong topic. The topic you need to post to is the state topic you defined for the IP address entity. According to the above, that topic should be "stat/TDSMonitor/ipaddress"... not the one with the sensor in it. Don't confuse the discovery topics with the topics you will use to publish values to those entities. So your publish statement to actually publish the IP address should be:
client.publish("stat/TDSMonitor/ipaddress", "10.0.0.14");
If you want to see a full example of the implementation of discovery, plus that device publishing its states to those sensors to update the values, you can take a peek at my car parking project. That can be found here: ESP Parking Assistant. Take a look at the .ino in the /src folder and you will see a full implementation. Some of the info in the wiki may also be helpful.
You're a wizard...thank you!
I will look at that project, im still stumbling my way through arduino and mqtt so there are some things where I look very silly and then you point it out and it's obvious 😅
Thank you again, please keep up the great content!
Using this code I am presented with the following error
2024-02-28 12:35:05.730 ERROR (MainThread) [homeassistant.components.sensor] Platform mqtt does not generate unique IDs. ID TDSMonF9D108tapTDS is already used by sensor.mqtt_tdsmonitor_taptds - ignoring sensor.mqtt_tdsmonitor_taptds_2
2024-02-28 12:35:05.734 ERROR (MainThread) [homeassistant.components.sensor] Platform mqtt does not generate unique IDs. ID TDSMonF9D108tapTDS is already used by sensor.mqtt_tdsmonitor_taptds - ignoring sensor.mqtt_tdsmonitor_taptds_2
2024-02-28 12:35:05.735 ERROR (MainThread) [homeassistant.components.sensor] Platform mqtt does not generate unique IDs. ID TDSMonF9D108tapTDS is already used by sensor.mqtt_tdsmonitor_taptds - ignoring sensor.mqtt_tdsmonitor_taptds_2
my equivalent code to yours is
void haDiscovery () {
char topic[128];
if (auto_discovery) {
char buffer1[512];
char buffer2[512];
char buffer3[512];
char buffer4[512];
char uid[128];
DynamicJsonDocument doc(512);
doc.clear();
Serial.println("Discovering new devices...");
} else {
}