ESP Scale with calibration and tare

 #include "HX711.h"

#include "Wire.h"

#include "Adafruit_SSD1306.h"

#include "ESP8266WiFi.h"

#include "EEPROM.h"

#include "ESP8266httpUpdate.h"

#define SCREEN_WIDTH 128 

#define SCREEN_HEIGHT 32 

#define OLED_RESET     -1 

#define SCREEN_ADDRESS 0x3C 

#define upd_version "1"

#define upd_reboot true

#define upd_server "10.11.12.13"

#define upd_file "/update/scaleupd.php"

const int LOADCELL_DOUT_PIN = D4;

const int LOADCELL_SCK_PIN = D3;

const int TarePin = D5;

const int OverPin = D6;

const int GoodPin = D7;

const int UnderPin = D8;

int CalEepromAdress = 101;

int TarEepromAdress = 111;

float known_mass = 500;

float readValue = 0;

float calValue = 6192.2;// overrided by EEPROM or/and boot calibration

float tareValue = 472; // overrided by EEPROM or/and manual tare

const char* ssid = "myWiFi";

const char* password = "53cr37p4ssw0rd"; 

HX711 scale;

WiFiClient client;

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET); //oled display uses std wire lib - for nodemcu SCL is D1(4), SDA is D2(5) (see pins_arduino.h)

void setup() {

  Serial.begin(115200);

  Serial.println("\nStarting...");

  display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS);

  display.clearDisplay();

  display.setTextSize(2);             

  display.setTextColor(SSD1306_WHITE);

  display.setCursor(0, 0);

  display.println("Press to  Calibrate");

  display.display(); 

  pinMode(TarePin, INPUT_PULLUP);

  pinMode(OverPin, OUTPUT);

  pinMode(GoodPin, OUTPUT);

  pinMode(UnderPin, OUTPUT);

  

  scale.begin(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN);

  delay(200); 

  scale.set_scale();

  scale.set_scale(calValue); 

  scale.tare();

 

  int wificnt = 0;

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED && wificnt < 10) {

   Serial.print (".");

   wificnt ++;

   delay(200);

  } //try 20sec to connect to Wifi in order to perform OTA update

  ESPhttpUpdate.rebootOnUpdate(upd_reboot);

  t_httpUpdate_return ret = ESPhttpUpdate.update(upd_server, 80, upd_file, upd_version);

  EEPROM.begin(512);

  EEPROM.get(CalEepromAdress, calValue);

  EEPROM.get(TarEepromAdress, tareValue);

 delay(2000); //Giving two sec to perform calibration at boot

  if(digitalRead(TarePin) == LOW){

   Serial.println("\nIn Calibration...");

   scale.set_scale();

   scale.tare();

   digitalWrite(UnderPin, HIGH); //turning all leds ON

   digitalWrite(OverPin, HIGH);

   digitalWrite(GoodPin, HIGH);

   display.clearDisplay();

   display.setCursor(0,0); 

   display.print("Calibrate with "); display.println(known_mass);

   display.display();      

   Serial.print("Calibrate with "); Serial.println(known_mass);

   delay(2000); //Two more seconds to release the button

   while (digitalRead(TarePin) == HIGH){ delay(200); Serial.print("."); } //Wait for the button to be pushed, after putting the calibrated weight on the scale

    calValue = (scale.get_units(10)) / known_mass;

    EEPROM.put(CalEepromAdress, calValue); //Save the calibration to EEPROM

    display.clearDisplay();

    display.setCursor(0,0); 

    display.print("Calibrated to "); display.println(calValue);

    display.display();

    Serial.print("\nCalibrated to "); Serial.println(calValue);

    scale.set_scale(calValue);

    delay(1000);

  }

  

  tareValue = (scale.get_units(20)); //Perform an initial tare

  scale.set_offset(tareValue);

  scale.tare();EEPROM.put(TarEepromAdress, tareValue); //Save TARE into EEPROM - not really needed here

  EEPROM.end();

 

}

void loop() {

 display.clearDisplay();

 

 if(digitalRead(TarePin) == LOW){ //if button pressed - perform tare

  Serial.println("\nTare...");

  digitalWrite(UnderPin, HIGH); //turn all leds on

  digitalWrite(GoodPin, HIGH);

  digitalWrite(OverPin, HIGH);

  

  tareValue = (scale.get_units(20)); 

  scale.set_offset(tareValue);

  display.clearDisplay();

  display.setTextSize(2);            

  display.setCursor(0,0);  

  display.print(" TARE to  "); display.println(tareValue);

  display.display(); 

  Serial.print("TARE to "); Serial.println(tareValue);

 } //end of TARE

 readValue = (scale.get_units(10) - tareValue);

 //readValue = (scale.read_average(20) - tareValue);

 Serial.println(readValue);

 display.clearDisplay();

 display.setTextSize(4);

 display.setCursor(5, 0);

 display.print(readValue); 

 display.setTextSize(2);

 display.setCursor(116, 17);

 display.println("g");

 display.display(); 

 digitalWrite(UnderPin, LOW); //turn all leds off

 digitalWrite(GoodPin, LOW);

 digitalWrite(OverPin, LOW);

 if(readValue < 3.49){

  digitalWrite(UnderPin, HIGH); //Red Led - below 3.5g 

 }

 if(readValue > 3.48 && readValue < 3.80){

  digitalWrite(GoodPin, HIGH); //Green Led - OK

 }

 if(readValue > 3.79){

  digitalWrite(OverPin, HIGH); //Blue Led - too heavy

 }  

//  delay(100);

}