// https://forum.arduino.cc/t/force-sensor-resistor-to-display-weight-and-voltage/1077247

#define FSR A0       // the FSR and 10K pulldown are connected to A0

int ledBLUE = 7;
int ledRED = 8;
int ledGREEN = 9;

void setup() 
{
  Serial.begin(9600);
  pinMode(ledBLUE, OUTPUT);
  pinMode(ledRED, OUTPUT);
  pinMode(ledGREEN, OUTPUT);
}

void loop() 
{
  int analogReading = analogRead(FSR);

  Serial.print("Force sensor reading = ");
  Serial.print(analogReading);    // print the raw analog reading

  if (analogReading < 10)         // from 0 to 9
  {
    Serial.println(" -> no pressure");
    digitalWrite(ledBLUE, LOW);
    digitalWrite(ledGREEN, LOW);
    digitalWrite(ledRED, LOW);
  }
  else if (analogReading < 200)   // from 10 to 199
  {
    Serial.println(" -> light touch");
    digitalWrite(ledBLUE, LOW);
    digitalWrite(ledGREEN, HIGH);
    digitalWrite(ledRED, LOW);
  }
  else if (analogReading < 800)   // from 500 to 799
  {
    Serial.println(" -> medium squeeze");
    digitalWrite(ledBLUE, HIGH);
    digitalWrite(ledGREEN, LOW);
    digitalWrite(ledRED, LOW);
  }
  else if (analogReading <= 1000)   // from 800 to 1000
  {
    Serial.println(" -> big squeeze");
    digitalWrite(ledBLUE, LOW);
    digitalWrite(ledGREEN, LOW);
    digitalWrite(ledRED, HIGH);
  }
  else
  {
    Serial.println(" -> something wrong ?");
    digitalWrite(ledBLUE, HIGH);
    digitalWrite(ledGREEN, HIGH);
    digitalWrite(ledRED, HIGH);
  }

  delay(1000);
}