#include <HX711.h>

char flag;
char ans;
float Gain = 1;

HX711 loadcell;

const int dout = 2;
const int sck = 4;

const long offset;
const long gain;

void setup() {
  Serial.begin(115200);
  loadcell.begin(dout,sck);

  loadcell.set_offset();
  loadcell.scale();

  Serial.println("");
  Serial.println("::: Force sensor :::");
  Serial.println("For offset compensation, press 'o' ;");
  Serial.println("For gain calibration, press 'g' ;");
  Serial.println("To start and stop real-time measurement, press 's' ;");
  Serial.println("::: end :::");
  Serial.println("");
}

void loop() {
  loadcell.set_scale();
  while (Serial.available()==0) {
  }

  flag = Serial.read();

  if(flag=='o') {
    OffsetComp();
  }

  if(flag=='g') {
    GainCalib();
  }

  if(flag=='s') {
    StartStop();
  }

  delay(1); // this speeds up the simulation
}

void OffsetComp() {
  Serial.println("Offset compensation - remove wire and leave every static load (pulley, bracket...)");
  delay(500);
  Serial.println("Press 'd' when done");
  ans = 'a';
  while (ans!='d') {
    if (Serial.available()>0) {
      ans = Serial.read();
    }
  }
  
  loadcell.tare();
  Serial.println("Tare done");
}

/* void GainChoice() {
  Serial.println("Gain calibration...");
  delay(500);
  Serial.println("Do offset compensation first ?");
  Serial.println("For 'yes', press 'y' ;");
  Serial.println("For 'no', press 'n' ;");

  while (Serial.available()==0) {
  }
  ans = Serial.read();

  if(ans=='n') {
    GainCalib();
  }

  if(ans=='y') {
    OffsetComp();
    GainCalib();
  }
} */

void GainCalib() {
  Serial.println("Gain calibration - add wire with weight ;");
  Serial.println("When stabilized, enter the weight value in kg :");
  
  int weight = 0;
  while (weight==0) {
    if (Serial.available()>0) {
      weight = Serial.parseInt();
    }
  }

  Serial.print("Weight = "); Serial.print(weight); Serial.println(" kg");
  
  Gain = loadcell.get_units(10)/weight;
  Serial.print("Gain = "); Serial.println(Gain);
  Serial.println("Gain calibration done");
}

void StartStop() {
  Serial.println("Reading");
  delay(500);
  char stop = 'a';
  while(stop!='s') {
    long reading = loadcell.get_units(10);
    Serial.println(reading);
    if (Serial.available()>0) {
      stop = Serial.read();
    }
  }
  Serial.println("Stop reading");
}