hx711 wiring

#include <HX711.h>
#include <EEPROM.h>

const byte DOUT_PIN        = 2;
const byte SCK_PIN         = 3;
const byte TARE_BUTTON_PIN = 7;

float calibrationFactor_lbs = 7050.0;
const float ZERO_BAND_LBS = 0.03;

#define EEPROM_MAGIC_ADDR   0
#define EEPROM_OFFSET_ADDR  1
#define EEPROM_MAGIC        0x42

long storedOffset = 0;

HX711 scale;

bool tareRequested = false;
unsigned long lastTareTime = 0;
const unsigned long TARE_COOLDOWN_MS = 2000;

void loadOrInitOffset();
void tareAndSaveOffset();
void checkTareButton();
float readWeightLbs();
void printWeightLbs();

void setup() {
  Serial.begin(115200);
  delay(500);

  pinMode(TARE_BUTTON_PIN, INPUT_PULLUP);

  scale.begin(DOUT_PIN, SCK_PIN);

  Serial.println(F("Initializing HX711..."));
  unsigned long start = millis();
  while (!scale.is_ready()) {
    if (millis() - start > 3000) {
      Serial.println(F("HX711 not ready after 3s, continuing anyway..."));
      break;
    }
  }

  scale.set_scale(calibrationFactor_lbs);
  loadOrInitOffset();
  scale.set_offset(storedOffset);

  Serial.println(F("Setup complete."));
  Serial.println(F("Press tare button to zero the scale."));
}

void loop() {
  checkTareButton();

  if (tareRequested) {
    unsigned long now = millis();
    if (now - lastTareTime > TARE_COOLDOWN_MS) {
      Serial.println(F("Tare button pressed, zeroing scale..."));
      tareAndSaveOffset();
      lastTareTime = now;
    }
    tareRequested = false;
  }

  printWeightLbs();
  delay(500);
}

void checkTareButton() {
  if (digitalRead(TARE_BUTTON_PIN) == LOW) {
    delay(50);
    if (digitalRead(TARE_BUTTON_PIN) == LOW) {
      tareRequested = true;
    }
  }
}

void loadOrInitOffset() {
  byte magic = EEPROM.read(EEPROM_MAGIC_ADDR);

  if (magic == EEPROM_MAGIC) {
    EEPROM.get(EEPROM_OFFSET_ADDR, storedOffset);
    Serial.print(F("Loaded offset from EEPROM: "));
    Serial.println(storedOffset);
  } else {
    Serial.println(F("No EEPROM data, performing initial tare..."));
    Serial.println(F("Make sure the scale is empty!"));

    scale.tare(10);
    storedOffset = scale.get_offset();

    EEPROM.put(EEPROM_OFFSET_ADDR, storedOffset);
    EEPROM.update(EEPROM_MAGIC_ADDR, EEPROM_MAGIC);

    Serial.print(F("Initial offset saved: "));
    Serial.println(storedOffset);
  }
}

void tareAndSaveOffset() {
  scale.tare(10);
  storedOffset = scale.get_offset();

  EEPROM.put(EEPROM_OFFSET_ADDR, storedOffset);
  EEPROM.update(EEPROM_MAGIC_ADDR, EEPROM_MAGIC);

  Serial.print(F("New offset saved: "));
  Serial.println(storedOffset);
}

float readWeightLbs() {
  const uint8_t samples = 20;
  float sum = 0.0;

  for (uint8_t i = 0; i < samples; i++) {
    checkTareButton();
    sum += scale.get_units(1);
    delay(5);
  }

  float avg = sum / samples;

  if (avg > -ZERO_BAND_LBS && avg < ZERO_BAND_LBS) {
    avg = 0.0;
  }

  return avg;
}

void printWeightLbs() {
  float pounds = readWeightLbs();

  Serial.print(F("Weight: "));
  Serial.print(pounds, 3);
  Serial.println(F(" lb"));
}