Senzorul de temperatura LM35 si Arduino

   Deoarece am prezentat tot felul de senzori de temperatura, am zis sa nu-l las deoparte nici pe LM35, care este unul din cele mai uzuale.
   Informatiile sunt cam aceleasi cu cele din articolul Senzorul de temperatura TMP36 (LM50) si Arduino, doar ca LM-ul nostru nu are acel offset, asa ca modul de conectare simplu, e bun pana pentru temperaturi pozitive:

iar montajul este foarte simplu:

   Am modificat foarte putin sketch-ul de la TMP36 si am obtinut:

   Sketch-ul modificat este:

// original sketch from http://learn.adafruit.com/tmp36-temperature-sensor/using-a-temp-sensor
// adapted sketch by niq_ro from http://nicuflorica.blogspot.com

//LMP35 Pin Variables
int sensorPin = 0; //the analog pin the LM35 Vout (sense) pin is connected to A0
                        //the resolution is 10 mV / degree centigrade with a
           
 /*
 * setup() - this function runs once when you turn your Arduino on
 * We initialize the serial connection with the computer
 */

// added part by niq_ro
float vmed = 0;
float ve = 0;  


void setup()
{
  Serial.begin(9600);  //Start the serial connection with the computer
                       //to view the result open the serial monitor 
}
 
void loop()                     // run over and over again
{
 vmed = 0;
 ve=0;
  
 for (int j = 0; j < 10; j++)  {
  
 //getting the voltage reading from the temperature sensor
 int reading = analogRead(sensorPin);  
    
 // converting that reading to voltage, for 3.3v arduino use 3.3
 float voltage = reading * 5.0;
 voltage /= 1024.0; 
 
 vmed = vmed + voltage;
 delay(200);
 
 }
 ve = vmed/10;
 
 // print out the voltage
 Serial.print(ve); Serial.println(" volts");
 
 // now print out the temperature
 float temperatureC = ve * 100 ;  //converting from 10 mv per degree 
                                               //to degrees (voltage) times 100)
 Serial.print(temperatureC); Serial.println(" degrees C");
 
 // now convert to Fahrenheit
 float temperatureF = (temperatureC * 9.0 / 5.0) + 32.0;
 Serial.print(temperatureF); Serial.println(" degrees F");
 Serial.println("----------------");
 delay(1000);                                     //waiting a second
}

   Deoarece e pacat sa nu folosim toata gama de masura, cu temperaturi negative, trebuie modificata foarte putin schema, prin adaugarea unei rezistente pe iesire si a 2 diode care "salta" tensiunea de iesire...

   Aceasta schema nu prea a fost tratata de utilizatorii Arduino, dar pot spune ca este prezentata in articolul Termometru cu Arduino de pe ROROID unde este/era si un brick (modul de masura):

   Am conectat si eu la fel pinii, pentru ca imi e greu sa redesenez acum, mentionand ca am folosit 2 diode 1N4007 si o rezistenta de 20k:

obtinand pe ecran citirile:

   Sketch-ul folosit este:

// original sketch from http://learn.adafruit.com/tmp36-temperature-sensor/using-a-temp-sensor
// adapted sketch by niq_ro from http://nicuflorica.blogspot.com
// LM35 datasheet: http://www.ti.com/lit/ds/symlink/lm35.pdf
// inspired by http://www.roroid.ro/wiki/pmwiki.php/Main/TermometruCuArduino

//LMP35 Pin Variables
int sensorPin = 0; //the analog pin the LM35 Vout (sense) pin is connected to A0
                        //the resolution is 10 mV / degree centigrade with a
int diodePin = 1;  //pin for measure voltage diode             

 /*
 * setup() - this function runs once when you turn your Arduino on
 * We initialize the serial connection with the computer
 */

// added part by niq_ro
float vmed = 0;
float ve = 0;  


void setup()
{
  Serial.begin(9600);  //Start the serial connection with the computer
                       //to view the result open the serial monitor 
}
 
void loop()                     // run over and over again
{
 vmed = 0;
 ve=0;
  
 for (int j = 0; j < 10; j++)  {
  
 //getting the voltage reading from the temperature sensor
 int reading = analogRead(sensorPin);  
 int reading1 = analogRead(diodePin);  
    
 // converting that reading to voltage, for 3.3v arduino use 3.3
 float voltage = reading * 5.0;
 voltage /= 1024.0; 
 float voltage1 = reading1 * 5.0;
 voltage1 /= 1024.0; 
 
 vmed = vmed + voltage - voltage1;
 delay(200);
 
 }
 ve = vmed/10;
 
 // print out the voltage
 Serial.print(ve); Serial.println(" volts");
 
 // now print out the temperature
 float temperatureC = ve * 100 ;  //converting from 10 mv per degree 
                                               //to degrees (voltage) times 100)
 Serial.print(temperatureC); Serial.println(" degrees C");
 
 // now convert to Fahrenheit
 float temperatureF = (temperatureC * 9.0 / 5.0) + 32.0;
 Serial.print(temperatureF); Serial.println(" degrees F");
 Serial.println("----------------");
 delay(1000);                                     //waiting a second
}

    Am scos LM-ul afara sa masor temperatura, ca-i frig: