Arduino Basic : RCtime

/*

/* RCtime
 *   Duplicates the functionality of the Basic Stamp's RCtime
 *   Allows digital pins to be used to read resistive analog sensors
 *   One advantage of this technique is that is can be used to read very wide ranging inputs.
 *   (The equivalent of 16 or 18 bit A/D)
 */

int sensorPin = 4;              // 220 or 1k resistor connected to this pin
long result = 0;
void setup()                    // run once, when the sketch starts
{
   Serial.begin(9600);
   Serial.println("start");      // a personal quirk
}
void loop()                     // run over and over again
{

   Serial.println( RCtime(sensorPin) );
   delay(10);

}

long RCtime(int sensPin){
   long result = 0;
   pinMode(sensPin, OUTPUT);       // make pin OUTPUT
   digitalWrite(sensPin, HIGH);    // make pin HIGH to discharge capacitor - study the schematic
   delay(1);                       // wait a  ms to make sure cap is discharged

   pinMode(sensPin, INPUT);        // turn pin into an input and time till pin goes low
   digitalWrite(sensPin, LOW);     // turn pullups off - or it won't work
   while(digitalRead(sensPin)){    // wait for pin to go low
      result++;
   }

   return result;                   // report results  
}