Changed PingPongPID to use Vernier library and eliminated notes for integrating VPython. I also modified PID parameters to work with my particular physical setup.

Author: Smythics

Diff for: VernierPingPongPID/VernierPingPongPID.ino

@@ -1,22 +1,13 @@
 /*
-VernierMotionDetectorPID (v 2015.05)
+VernierMotionDetectorPID (v 2017.08)
 Takes data from a Vernier Motion Detector connected to Digital 1 connector. 
 Uses PID to control fan to elevate ping pong ball to target height. The ball is in
 plastic tube 0.6 m tall with a fan at the bottom and a motion detector at the top. 
 This version uses a Digital Control Unit (DCU) connected to the Digital 2 port to 
 control the fan.
 
-Motion detector portion of this sketch is taken from VernierMotionDetector (v 2014.09) 
-It measures the time taken for the ultrasound to return (in microseconds)
-and then calculates the corresponding distance (based on the speed of ultrasound
-in air) and displays the distance (in cm) on the Serial Monitor. 
-
-Here is how the Vernier Motion Detector works:
-- when pin 2 on BTD is pulled high, this triggers the ultrasound pulse
-- the program then starts timing but then delays 0.9 ms *(blanking time,
-   0.9 seconds is the time it takes ultrasound to travel 15 cm twice (round trip))
-- the program then monitors pin 1 on the BTD, waiting for it to go high. 
-This happens when an echo is detected.
+Motion detector is read using the Vernier Library that calculates the distance based
+the echo of an ultrasonic sound wave. 
 
 The PID control is modified from http://playground.arduino.cc/Code/PIDLibaryBasicExample 
 and takes the calculated input from the motion detector ("distance") and controls analog PWM
@@ -26,111 +17,59 @@ http://playground.arduino.cc/Code/PIDLibrary.
 As written, the reading will feed to the PID control continuously and data fed to
 Serial Print.
 
-This has been used with VPython to create a virtual display of the ping pong ball. 
-Some notes in the sketch are there to aid ease of reading data into VPython.
+There are several ways you can modify this. We have previously linked the output 
+of this program to VPython to create a virtual display of the ping pong ball. 
+Search the internet for tips on combining Arduino and VPython. You can also vary 
+set point so that it seeks a variety of heights - definitely more eye catching.
   
 See www.vernier.com/arduino for more information.
  */
+ 
 #include <PID_v1.h>
+#include "VernierLib.h" 
+VernierLib Vernier;
+double setPoint, distance, output; //define variables we'll be connecting to
+PID myPID(&distance, &output, &setPoint, 3,6.0,6.0, REVERSE); 
+/*Specify the links and initial tuning parameters. These work for a system
+with a 0.6 m tube and the particular fan we are using. Depends on power supply 
+to the fan as well as cowling around fan.*/
 
-//Define Variables we'll be connecting to
-double Setpoint, Distance, Output;
-
-//Specify the links and initial tuning parameters
-PID myPID(&Distance, &Output, &Setpoint, 9,1.0,2.0, REVERSE);
-
-const int TriggerPin = 3; //trigger pin
-const int EchoPin = 2;// echo pin
-
-void setup() 
+void setup()
 {
-  // initialize the Ping pin as an output:
-  pinMode(TriggerPin, OUTPUT);
-  pinMode(EchoPin, INPUT); //this is the pin that goes high when an echo is received
-   
-  Setpoint = 30; // setpoint (cm from top)
-
-  //turn the PID on
-  myPID.SetMode(AUTOMATIC);
-  
-  // initialize serial communication at 9600 bits per second:
   Serial.begin(9600);
-  // The following can be grayed out for a VPython serial display
+
+  setPoint = 40; // setpoint (cm from top)
+  myPID.SetMode(AUTOMATIC); //turn the PID on
+
   Serial.println("Vernier Format 2");
   Serial.println("Motion Detector Readings taken using Ardunio");
   Serial.println("Data Set");
-  Serial.print("Time for Echo");//long name
-  Serial.print("\t"); //tab character
+
   Serial.print("Set Point");
   Serial.print("\t"); // tab character
   Serial.print ("Distance"); //long name
   Serial.print("\t");
   Serial.println ("Output from PID"); 
-  Serial.print("delta t");//short name
-  Serial.print("\t"); //tab character
-  Serial.print("\t"); //tab character
-  Serial.print("SP");
-  Serial.print("\t"); // tab character
+
+  Serial.print("SP (cm)");
+  Serial.print("\t"); 
   Serial.print("\t");
-  Serial.print ("D"); //short name
+  Serial.print ("d (cm)"); //short name
   Serial.print("\t");
   Serial.print("\t");
   Serial.println("0 - 255");
-  Serial.print("micro seconds");//units
-  Serial.print("\t"); // tab character
-  Serial.print ("cm"); //units
-  Serial.print("\t"); // tab character
-  Serial.print("\t");
-  Serial.print ("cm"); //units
-  Serial.print("\t");
-  Serial.print("\t");
-  Serial.println("#");
-  // This would be the end of the grayed out portion if using VPython
-}
+  }
 void loop() 
 {
-  long time; // clock reading in microseconds
-  long Duration; // time it take echo to return
-  const float SpeedOfSound = 340; //in m/s
-  int val = 0;
-  digitalWrite(TriggerPin, LOW);
-  delayMicroseconds(4000);
-  digitalWrite(TriggerPin, HIGH); // start the ultrasound pulse
-  time = micros(); //note time
-  delayMicroseconds(900); //delay during the blanking time
-  do
-  {
-    val =digitalRead(EchoPin);
-    // if no echo, repeat loop and wait:
-  }
-  while (val == LOW) ;
-  Duration =micros() - time;
-  
-  /* The speed of sound is 340 m/s.
-  The ultrasound travels out and back, so to find the distance of the
-  object we take half of the distance traveled.*/
-  
-  Distance= Duration *SpeedOfSound/2/10000 ;// note convert to cm
-  
+  distance = Vernier.readMotionDetector();
   myPID.Compute();
-  analogWrite(6,Output);
-  
-  //* Grayed out for python connection
-  Serial.print(Duration);// print the time it took until the echo
-  Serial.print("\t"); // tab character
-  Serial.print("\t");
-  Serial.print(Setpoint);
-  Serial.print("\t"); // tab character
+  analogWrite(6,output);
+  Serial.print(setPoint);
+  Serial.print("\t"); 
   Serial.print("\t");
-  // This would be the end of the grayed out portion
-  Serial.print(Distance);
+  Serial.print(distance);
   Serial.print("\t");
-  Serial.print("\t"); //tab character
-  Serial.println(Output);
-  delay (100);
- 
+  Serial.print("\t"); 
+  Serial.println(output);
+  delay (10);
 }
-
- 
-
-