HX711+ESP8266+MQTT

chemejonHX711MQTTExample.ino

#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include "HX711.h" 

const char* ssid = "Your SSID";
const char* password = "Your Password";
const char* mqtt_server = "Your MQTT Server Ip";
WiFiClient espClient;
PubSubClient client(espClient);
#define DOUT  14
#define CLK  12
char msg_buff[50];


int switchPin = 5;
int switchValue;
HX711 scale(DOUT, CLK);
//Change this calibration factor as per your load cell once it is found you many need to vary it in thousands
float calibration_factor = -219.50; //-219.50 worked for my scale 

//=============================================================================================
//                         SETUP
//=============================================================================================
void setup() {
  delay(100);
  pinMode(BUILTIN_LED, OUTPUT);
  pinMode(switchPin, INPUT_PULLUP);
  Serial.begin(115200);
  Serial.println("HX711 Calibration");
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
  scale_setup();

  
}
void scale_setup() {
  client.subscribe("HX711cal"); 
  Serial.println("HX711 Calibration");
  Serial.println("Remove all weight from scale");
  Serial.println("After readings begin, place known weight on scale");
  Serial.println("Press a,s,d,f to increase calibration factor by 10,100,1000,10000 respectively");
  Serial.println("Press z,x,c,v to decrease calibration factor by 10,100,1000,10000 respectively");
  Serial.println("Press t for tare");
  scale.tare(); //Reset the scale to 0
  delay(1000);
  scale.tare();
  delay(500);
  scale.tare();
  digitalWrite(BUILTIN_LED, HIGH);
  delay(1000);
  digitalWrite(BUILTIN_LED, LOW);
}

void setup_wifi(){
  delay(10);
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void reconnect() {
  while(!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (client.connect("ESP8266Client")) {
      Serial.println("connected");
      client.subscribe("HX711cal");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
      
    }
  }
}

void callback(char* topic, byte* payload, unsigned int length) {
   int i = 0;
  Serial.println("Message arrived:  topic: " + String(topic));
  Serial.println("Length: " + String(length,DEC));
  for(i=0; i<length; i++) {
    msg_buff[i] = payload[i];
  }
  msg_buff[i] = '\0';
  
  String msgString = String(msg_buff);
  
  Serial.println("Payload: " + msgString);
  if (msgString == "tare"){    // if there is a "1" published to any topic (#) on the broker then:
    digitalWrite(BUILTIN_LED, LOW);     // set pin to the opposite state 
    Serial.println("Switching LED");
    scale.tare(5);
    digitalWrite(BUILTIN_LED, HIGH);
  }
  else if (msgString == "+0.1")
     calibration_factor += 0.1;
  else if(msgString == "-0.1")
      calibration_factor -= 0.1;
  else if(msgString == "+1")
      calibration_factor += 1;  
  else if(msgString == "-1")
      calibration_factor -= 1;  
  else if(msgString == "+10")
      calibration_factor += 10;  
  else if(msgString == "-10")
      calibration_factor -= 10;
  else if(msgString == "+100")
      calibration_factor += 100;  
  else if(msgString == "-100")
      calibration_factor -= 100;  
}

//=============================================================================================
//                         LOOP
//=============================================================================================
void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  float weight = scale.get_units(15);
  float rounded = round(weight) ;

  scale.set_scale(calibration_factor); //Adjust to this calibration factor
  switchValue = digitalRead(switchPin);
  Serial.print("Reading: ");
  Serial.print(weight);
  Serial.print(" g"); //Change this to kg and re-adjust the calibration factor if you follow SI units like a sane person
  Serial.print(" calibration_factor: ");
  Serial.print(calibration_factor);
  Serial.println();
  Serial.println(switchValue);
  client.publish("Scale1",String(rounded).c_str(),true);
  client.publish("Debug",String(weight).c_str(),true);
  client.publish("HX711calfactor",String(calibration_factor).c_str(),true);
  if(switchValue == 1){
    digitalWrite(BUILTIN_LED, LOW);
    scale.tare(5);
    digitalWrite(BUILTIN_LED, HIGH);
  }
  
  
  

  if(Serial.available())
  {
    char temp = Serial.read();
    if(temp == '+' || temp == 'a')
      calibration_factor += 0.1;
    else if(temp == '-' || temp == 'z')
      calibration_factor -= 0.1;
    else if(temp == 's')
      calibration_factor += 1;  
    else if(temp == 'x')
      calibration_factor -= 1;  
    else if(temp == 'd')
      calibration_factor += 10;  
    else if(temp == 'c')
      calibration_factor -= 10;
    else if(temp == 'f')
      calibration_factor += 100;  
    else if(temp == 'v')
      calibration_factor -= 100;  
    else if(switchValue == '0');
      scale.tare(5);  //Reset the scale to zero
    else if(temp='t')
      scale.tare(5);  //Reset the scale to zero
  }
}
//=============================================================================================

Hi. I found something in your code. I tried to compile and got an error.
Line 176-179

else if(switchValue == '0');
     scale.tare(5);  //Reset the scale to zero
else if(temp='t')
     scale.tare(5); //Reset the scale to zero

I has to be like (error is gone and beautyfying)

else if(temp='t')
     scale.tare(5); //Reset the scale to zero
else if(switchValue == '0');
     scale.tare(5);  //Reset the scale to zero

But the code doesn't work either. I just got

Connecting to my_WLAN
......
WiFi connected
IP address:
10.10.10.10
HX711 Calibration
Remove all weight from scale
After readings begin, place known weight on scale
Press a,s,d,f to increase calibration factor by 10,100,1000,10000 respectively
Press z,x,c,v to decrease calibration factor by 10,100,1000,10000 respectively
Press t for tare

then it ends. Some ideas?

Have you solved this issue. I still strugle with it.

The problem is probably with different libraries for the HX711 this code was pulled from a production environment and was verified to work with my version of the library. You might want to open your specific HX711 library and look at the proper calls are like 17 specifically. You might need to replace HX711 scale(DOUT, CLK); with HX711 scale; then add scale.begin(DOUT, CLK); for example