Dimmer and ESP8266 with MQTT connecting to Home Assistant.

/******************************************************************************
Example_Dimmer1L_ESP8266_HA.ino
Example for controlling a dimmer using an MQTT HA slider
by: RobotDyn

This sketch connects the ESP8266 to a MQTT broker and subcribes to the topic
dimmer/power. When the slider is pressed, the client will change a dimming level from 0 to 99.
******************************************************************************/
#include <RBDdimmer.h>
#define outputPin  4 
#define zerocross  5 // for boards with CHANGEBLE input pins

dimmerLamp dimmer(outputPin, zerocross); //initialase port for dimmer for ESP8266


#include <ESP8266WiFi.h>
#include <PubSubClient.h>

// WiFi Network Credentials
const char *ssid =  "_____";   // name of your WiFi network
const char *password =  "_____"; // password of the WiFi network

// Home Assistant Credentials. Optional if HA MQTT have user.
const char *HA_USER = "_____";
const char *HA_PASS = "_____";

// MQTT Network
IPAddress broker(xxx,xxx,xxx,xxx); // IP address of your MQTT broker eg.
const char *ID = "Example_Dimmer";  // Name of our device, must be unique!!!
const char *TOPIC = "dimmer/power";  // Topic to subcribe to
char *STATE_TOPIC = "dimmer/power/state";  // Topic to publish the light state to

char msg[50];

WiFiClient wclient;

PubSubClient client(wclient); // Setup MQTT client

// Handle incomming messages from the broker
void callback(char* topic, byte* payload, unsigned int length) {
  String response;
  int power_L;  
  
  for (int i = 0; i < length; i++) {
    response += (char)payload[i];
  }
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  Serial.println(response);
  power_L=response.toInt();
      dimmer.setPower(power_L);
      delay(50);
      snprintf (msg, 50, "%ld", dimmer.getPower());
      client.publish(STATE_TOPIC, msg);
      Serial.print("State ");
      Serial.println(msg);

  
}

// Connect to WiFi network
void setup_wifi() {
  Serial.print("\nConnecting to ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) { // Wait for connection
    delay(500);
    Serial.print(".");
  }

  Serial.println();
  Serial.println("WiFi connected");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
}

// Reconnect to client
void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if(client.connect(ID,HA_USER,HA_PASS)) {
      client.subscribe(TOPIC);
      Serial.println("connected");
      Serial.print("Subcribed to: ");
      Serial.println(TOPIC);
      Serial.println('\n');
    } else {
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void setup() {
  dimmer.begin(NORMAL_MODE, ON); //Initialize the dimmer
  Serial.begin(115200); // Start serial communication at 115200 baud
 
  delay(100);
  setup_wifi(); // Connect to network
  client.setServer(broker, 1883);
  client.setCallback(callback);// Initialize the callback routine
}

void loop() {
  if (!client.connected())  // Reconnect if connection is lost
  {
    reconnect();
  }
  client.loop();
}

light:    
  - platform: mqtt
    name: "Example_Dimmer"
    state_topic: "dimmer/power/state"
    command_topic: "dimmer/power"
    on_command_type: brightness
    payload_on:                    "99"
    payload_off:                   "1"
    brightness_state_topic: "dimmer/power/state"
    brightness_command_topic: "dimmer/power"
    brightness_scale:              99
    qos:                           1
    retain:                        true
    optimistic:                    false