// ATtiny85 Blink!
#include <TinyWireM.h>
#include <Tiny4kOLED.h>

#define sensor              3
#define rele                1
#define THERMISTOR         992                 // VALOR OHM DEL SENSOR 25 °C(992 spark)(2500 optra)
#define NUMSAMPLES         10                  // NUMERO DE MUESTRAS TOMADAS NTC
#define BCOEFFICIENT       3680                // beta coefficient 3000-4000 (3680 spark) 
#define SERIESRESISTOR     974                 // resistor en serie 10k (1k para spark)

unsigned long timer;

void setup() { 
 pinMode(rele, OUTPUT);     
 pinMode(sensor, INPUT);  
 digitalWrite(rele, LOW); 
  oled.begin(128, 64, sizeof(tiny4koled_init_128x64br), tiny4koled_init_128x64br);
  oled.on();
}

void loop() {
  float Rth, steinhart, average=0;  char i;  int samples[NUMSAMPLES];                                               
  for (i=0; i< NUMSAMPLES; i++) { samples[i] = analogRead(sensor); } 
  for (i=0; i< NUMSAMPLES; i++) { average += samples[i]; }
  average /= NUMSAMPLES;                                                        
  Rth = (1024 * float(THERMISTOR)/average)-float(THERMISTOR);                             //Valor de Rth en funcion del conexionado de nuestro termistor
  steinhart = ((1/((1/298.15)+(1/float(BCOEFFICIENT))*log(SERIESRESISTOR/Rth)))-273.15);    //Aplicamos directamente Steinhart-hart para NTC                                           
//****************************************************************************************//
  if (millis() > timer) { oled.clear(); timer = millis() + 3000UL; } 
  oled.setFont(FONT6X8);
  oled.setCursor(32,0); oled.println(F("TEMPERATURA"));
  oled.setFont(FONT8X16);
  oled.setCursor(35,3); oled.print(steinhart,1); oled.println(F(" 'C")); 
  if (steinhart>=92) {digitalWrite(rele,HIGH); 
  oled.setCursor(40,5); oled.println(F("FAN On"));}
  if (steinhart<90)  {digitalWrite(rele,LOW);}
        }