dwbPulseTimerInterrupt1Thermistor.ino

// temp variables 

// which analog pin to connect
#define THERMISTORPIN A0         
// resistance at 25 degrees C
#define THERMISTORNOMINAL 10000      
// temp. for nominal resistance (almost always 25 C)
#define TEMPERATURENOMINAL 25   
// how many samples to take and average, more takes longer
// but is more 'smooth'
#define NUMSAMPLES 5
// The beta coefficient of the thermistor (usually 3000-4000)
#define BCOEFFICIENT 3950
// the value of the 'other' resistor
#define SERIESRESISTOR 10000  

int samples[NUMSAMPLES];


// conductivity variables

long pulseCount = 0;  //a pulse counter variable

unsigned long pulseTime,lastTime, duration, totalDuration;

int samplingPeriod=2; // the number of seconds to measure 555 oscillations

int fivefivefive = 13; // the pin that powers the 555 subcircuit

void setup()
{
  Serial.begin(9600);
  
      pinMode(fivefivefive, OUTPUT);   
           
}

void loop()
{
   uint8_t i;
  float average;
  
  
  delay(1000); // imagine riffle is doing other stuff (like sleeping)
  
  // now make a conductivity measurement
  
  
  // temperature ---------------------------------------------
 
 
  // take N samples in a row, with a slight delay
  for (i=0; i< NUMSAMPLES; i++) {
   samples[i] = analogRead(THERMISTORPIN);
   delay(10);
  }
  
  // average all the samples out
  average = 0;
  for (i=0; i< NUMSAMPLES; i++) {
     average += samples[i];
  }
  average /= NUMSAMPLES;
 
  // convert the value to resistance
  average = 1023 / average - 1;
  average = SERIESRESISTOR / average;
  //Serial.print("Thermistor resistance "); 
  //Serial.println(average);
 
  float steinhart;
  steinhart = average / THERMISTORNOMINAL;     // (R/Ro)
  steinhart = log(steinhart);                  // ln(R/Ro)
  steinhart /= BCOEFFICIENT;                   // 1/B * ln(R/Ro)
  steinhart += 1.0 / (TEMPERATURENOMINAL + 273.15); // + (1/To)
  steinhart = 1.0 / steinhart;                 // Invert
  steinhart -= 273.15;                         // convert to C
 
  //Serial.print(steinhart);
  //Serial.println(" *C");
  
  
  // conductivity --------------------------------------
  
  //turn on the 555 system
  digitalWrite(fivefivefive,HIGH); //turns on the 555 timer subcircuit
  
  pulseCount=0; //reset the pulse counter
  totalDuration=0;  //reset the totalDuration of all pulses measured
  
  attachInterrupt(1,onPulse,RISING); //attach an interrupt counter to interrupt pin 1 (digital pin #3) -- the only other possible pin on the 328p is interrupt pin #0 (digital pin #2)
  
  pulseTime=micros(); // start the stopwatch
  
  delay(samplingPeriod*1000); //give ourselves samplingPeriod seconds to make this measurement, during which the "onPulse" function will count up all the pulses, and sum the total time they took as 'totalDuration' 
 
  detachInterrupt(1); //we've finished sampling, so detach the interrupt function -- don't count any more pulses
  
  //turn off the 555 system
  digitalWrite(fivefivefive,LOW);
  
  if (pulseCount>0) { //use this logic in case something went wrong
  
  double durationS=totalDuration/double(pulseCount)/1000000.; //the total duration, in seconds, per pulse (note that totalDuration was in microseconds)
  
  // print out stats
  /*Serial.print("sampling period=");
  Serial.print(samplingPeriod);
    Serial.print(" sec; #pulses=");
  Serial.print(pulseCount);
  Serial.print("; duration per pulse (sec)=");
  */
  
  // print conductivity value
  Serial.print(durationS,4);
  Serial.print(", ");
  Serial.println(steinhart);
  }
  }
  

void onPulse()
{
  pulseCount++;
  //Serial.print("pulsecount=");
  //Serial.println(pulseCount);
  lastTime = pulseTime;
  pulseTime = micros();
  duration=pulseTime-lastTime;
  totalDuration+=duration;
  //Serial.println(totalDuration);
}