/* The circuit:
	* +V connection of the PING))) attached to +5V
	* GND connection of the PING))) attached to ground
	* SIG connection of the PING))) attached to digital pin 7 */
const int tankPingPin = 7;
const int snowPingPin = 28;

float getPingGallons() {
   // The PING))) is triggered by a HIGH pulse of 2 or more microseconds.
  // Give a short LOW pulse beforehand to ensure a clean HIGH pulse:
  // establish variables for duration of the ping, 
  // and the distance result in inches and centimeters:
  long duration;
  float inches, depth, gallons;
  pinMode(tankPingPin, OUTPUT);
  digitalWrite(tankPingPin, LOW);
  delayMicroseconds(2);
  noInterrupts();
  digitalWrite(tankPingPin, HIGH);
  delayMicroseconds(5);
  
  digitalWrite(tankPingPin, LOW);

  // The same pin is used to read the signal from the PING))): a HIGH
  // pulse whose duration is the time (in microseconds) from the sending
  // of the ping to the reception of its echo off of an object.
  pinMode(tankPingPin, INPUT);
  duration = pulseIn(tankPingPin, HIGH);
  interrupts();

  // convert the time into a distance
  inches = duration / 74.0 / 2.0;;
    
  // convert to depth and gallons
  // real tank: depth = 63 - inches;
  depth = 13.61f - inches;
  if (depth < 0) depth = 0;
  gallons = depth / 2.63f;
  
  Serial.print(inches);
  Serial.print("in, ");
  Serial.print(depth);
  Serial.print("depth, ");
  Serial.print(gallons);
  Serial.print("gallons");
  Serial.println();
  return(gallons);
}

float getSnowInches() {
  long duration;
  float inches, depth;
  pinMode(snowPingPin, OUTPUT);
  digitalWrite(snowPingPin, LOW);
  delayMicroseconds(2);
  noInterrupts();
  digitalWrite(snowPingPin, HIGH);
  delayMicroseconds(5);
  
  digitalWrite(snowPingPin, LOW);

  // The same pin is used to read the signal from the PING))): a HIGH
  // pulse whose duration is the time (in microseconds) from the sending
  // of the ping to the reception of its echo off of an object.
  pinMode(snowPingPin, INPUT);
  duration = pulseIn(snowPingPin, HIGH);
  interrupts();

  // convert the time into a distance
  inches = duration / 74.0 / 2.0;;
    
  // convert to snow depth 
  depth = 36.0f - inches;
  if (depth < 0) depth = 0;
  Serial.print("Snow: ");
  Serial.print(inches);
  Serial.print("in, ");
  Serial.print(depth);
  Serial.print("depth, ");
  Serial.println();
  return(depth);
}