eeprom-temperature.ino

#include <EEPROM.h>

const int buttonPin = 12; // the number of the pushbutton pin
const int ledPin = 13; // the number of the LED pin
const int temperaturePin = A0;

float minTemp, maxTemp; // Variables to store min and max temperature

int buttonState = 0; // variable for reading the pushbutton status

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(buttonPin, INPUT_PULLUP);
  pinMode(ledPin, OUTPUT);
  EEPROM.put(0, 25);
  EEPROM.put(8, 25);
  minTemp = 100.00;
  maxTemp = -100.00;
  printTemp();
}

void loop() {
  // put your main code here, to run repeatedly:
  // read the state of the pushbutton value:
  buttonState = digitalRead(buttonPin);

  saveReadings();

  // check if the pushbutton is pressed. If it is, the buttonState is HIGH:
  if (buttonState == LOW) {
    // turn LED on:
    digitalWrite(ledPin, HIGH);
    printTemp();
  } else {
    // turn LED off:
    digitalWrite(ledPin, LOW);
  }
}

void printTemp() {
  float storedMinTemp, storedMaxTemp;
  EEPROM.get(0, storedMinTemp);
  EEPROM.get(8, storedMaxTemp);
  Serial.print("Min: ");
  Serial.print(storedMinTemp);
  Serial.print(" Max: ");
  Serial.println(storedMaxTemp);
  delay(200);
}

void saveReadings() {

  float voltage, degreesC, degreesF; //Declare 3 floating point variables
  voltage = getVoltage(temperaturePin); //Measure the voltage at the analog pin
  degreesC = (voltage - 0.5) * 100.0; // Convert the voltage to degrees Celsius

  if (degreesC < minTemp) { // minThreshold was initialized to 1023 -- so, if it's less, reset the threshold level.
    minTemp = degreesC;
  }

  if (degreesC > maxTemp) { // maxThreshold was initialized to 0 -- so, if it's bigger, reset the threshold level.
    maxTemp = degreesC;
  }

  EEPROM.put(0, minTemp);
  EEPROM.put(8, maxTemp);

}

//Function to read and return
//floating-point value (true voltage)
//on analog pin 

float getVoltage(int pin) {

  return (analogRead(pin) * 0.004882814);
  // This equation converts the 0 to 1023 value that analogRead()
  // returns, into a 0.0 to 5.0 value that is the true voltage
  // being read at that pin.
}