/*
  Conditionals - If statement
 
  This example demonstrates the use of if() statements.
  It reads the state of a potentiometer (an analog input) and turns on a particular LED
  only if the potentiometer goes above a certain threshold level. It prints the
  analog value regardless of the level.  A high threshold range will light a red LED, a middle range will light a yellow LED
  and a low range will light a green LED
 
  The circuit:
  - potentiometer
    Center pin of the potentiometer goes to analog pin 0.
    Side pins of the potentiometer go to +5V and ground.
  - LED connected from digital pins to ground through 220 ohm resistors
 
  - Note: On most Arduino boards, there is already an LED on the board connected
    to pin 13, so you don't need any extra components for this example.

 
  This example code is in the public domain.
 
  https://www.arduino.cc/en/Tutorial/BuiltInExamples/ifStatementConditional
  
  
  
  Class Exercise 
  1. Change the program to light the red LED when the analog input is greater than 700, 
  2. Light the yellow LED  between 300 to 699, 
  3. Green LED 299 to 100 and all three LEDs should light when the value is below 100.
*/
 
// These constants won't change:
const int analogPin = A0;   // pin that the sensor is attached to
const int ledPinR = 13;      // pin that the Red LED is attached to
const int ledPinY = 11;      // pin that the Yellow LED is attached to
const int ledPinG = 9;      // pin that the Green LED is attached to
const int thresholdHigh = 700;  // an arbitrary threshold level that's in the range of the analog input
const int thresholdMed = 300;  // an arbitrary threshold level that's in the range of the analog input
const int thresholdLow  =  100;  // low value threshold level
void setup()
{
  // initialize the LED pin as an output:
  pinMode(ledPinR, OUTPUT);
  pinMode(ledPinY, OUTPUT);
  pinMode(ledPinG, OUTPUT);
  // initialize serial communications:
  Serial.begin(9600);
}
 
void loop()
{
  // read the value of the potentiometer:
  int analogValue = analogRead(analogPin);
  digitalWrite(ledPinR, LOW);
  digitalWrite(ledPinY, LOW);
  digitalWrite(ledPinG, LOW);
 
  // if the analog value is high enough, turn on the LED:
  // If the resistance value is greater than or equal to 700 ohms, turn on Red LED
  if (analogValue >= thresholdHigh)
  {
    digitalWrite(ledPinR, HIGH);
  }
  // if the resistance value is between 300 to 699 ohms, turn on Yellow LED
  else if ((analogValue > thresholdMed) && (analogValue < thresholdHigh-1))
  {
    digitalWrite(ledPinY, HIGH);
  }
  // If the resistance value is between 100 and 299 turn on Green LED
  else if ((analogValue > thresholdLow) && (analogValue < thresholdMed-1))
  {
    digitalWrite(ledPinG, HIGH);
  }
  else // Otherwise the resistance value is less than 100 turn on all LED's
  {
    digitalWrite(ledPinR, HIGH);
    digitalWrite(ledPinY, HIGH);
    digitalWrite(ledPinG, HIGH);
  }

 
  // print the analog value:
  Serial.println(analogValue);
  delay(1);  // delay in between reads for stability
}