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Hi

I have a LV-MaxSonar EZ1 and I using this code to get readouts of distance measurements.  This is the code that I am using for that:

Code:

//Feel free to use this code.
//Please be respectful by acknowledging the author in the code if you use or modify it.
//Author: Bruce Allen
//Date: 23/07/09

//Digital pin 7 for reading in the pulse width from the MaxSonar device.
//This variable is a constant because the pin will not change throughout execution of this code.
const int pwPin = 7;

//variables needed to store values
long pulse, inches, cm;


void setup() {
  //This opens up a serial connection to shoot the results back to the PC console
  Serial.begin(9600);
}


void loop() {
  pinMode(pwPin, INPUT);
    //Used to read in the pulse that is being sent by the MaxSonar device.
  //Pulse Width representation with a scale factor of 147 uS per Inch.

  pulse = pulseIn(pwPin, HIGH);
  //147uS per inch
  inches = pulse/147;
  //change inches to centimetres
  cm = inches * 2.54;
  Serial.print(inches);
  Serial.print("in, ");
  Serial.print(cm);
  Serial.print("cm");
  Serial.println();
  delay(500);
}

I have a potentiometer that sends MIDI data over a DIN-5 MIDI connector attached to my breadboard using this code:

Code:

/*
 * 7.1 Midi OUT controller
 * roguescience.org
 *
 * digital pin 11 (OUTPUT/PWM) --> LED
 * digital pin 2 (INPUT) <-- button
 * analog pin 0 <-- pot
 * tx1 <-- pin 5 (5 PIN DIN aka MIDI jack)
 *
 * Send a MIDI note when the button is pressed and sends MIDI
 * CC data when a potentiometer is turned.
 */

int ledPin = 11;                //choose the pin for the LED - needs to be (3,5,6,9,10, or 11)
int buttonPin = 2;               //choose the input pin for a pushbutton
int potPin = 0;                  //choose the input pin for a potentometer
int buttonVal = 0;                    //variable for reading the button status
int buttonState = 0;            //variable to hold the buttons current state
int bounceCheck = 0;            //variable for debouncing
int potVal = 0;                //variable for reading potentiometer value
int mappedPotVal = 0;          //variable for holding remapped pot value
int prevPotVal = 0;               //variable for storing our prev pot value
int THRESHOLD = 2;            //threshold amount

void setup() {
  pinMode(ledPin, OUTPUT);      //declare LED as output
  pinMode(buttonPin, INPUT);     //declare pushbutton as input
  Serial.begin(31250);            //MIDI communicates at 31250 baud
}

void loop(){

  buttonVal = digitalRead(buttonPin);     //read input value from button
  delay(10);                              //wait 10ms
  bounceCheck = digitalRead(buttonPin);   //check again
  if(buttonVal == bounceCheck){           //if val is the same then not a bounce
    if (buttonVal == HIGH && buttonState == 1) {   //check if the input is HIGH
      digitalWrite(ledPin, LOW);         //turn LED OFF
      midiOUT(0x90, 60, 0); //Note ON (CH 1), middle C, zero velocity turns note off
      buttonState = 0;
    }
    if(buttonVal == LOW && buttonState == 0){
      digitalWrite(ledPin, HIGH);       //turn LED ON
      midiOUT(0x90, 60, 127); //Note ON (CH 1), middle C, velocity 127
      buttonState = 1;
    }

  }

   potVal = analogRead(potPin);         //read input from potentiometer
   mappedPotVal = map(potVal, 0, 1023, 0, 127);  //map value to 0-127
   if(abs(mappedPotVal - prevPotVal) >= THRESHOLD){
     midiOUT(0xB0, 7, mappedPotVal); //Control Change (Ch 1), Controller 7 - default control for volume.
     digitalWrite(ledPin, HIGH);
     prevPotVal = mappedPotVal;
   }
   else{
      digitalWrite(ledPin, LOW);
   }

}

void midiOUT(char command, char value1, char value2) {
  Serial.print(command, BYTE);
  Serial.print(value1, BYTE);
  Serial.print(value2, BYTE);

}

The Sonar is inputting values over Pulse Width, whereas the Pot in the MIDI example is inputting values through an Analog pin.


What code will I need to replace the Analog Potentiometer with a Sonar input over Pulse Width?

Thanks

[Reply #1 on:]

Code:

   potVal = analogRead(potPin);         //read input from potentiometer

Here, potVal is a number that relates to the position of the pot wiper.

Code:

  pulse = pulseIn(pwPin, HIGH);

Here, pulse is a number that relates to the distance to whatever the ping sensor is seeing.

Code:

   mappedPotVal = map(potVal, 0, 1023, 0, 127);  //map value to 0-127

Here, the potVal is mapped to a range of 0-127.

You need something like

Code:

   mappedPulse = map(pulse, start, end, 0, 127);  //map value to 0-127

You will need to work out the start and end of the range of numbers that the ping sensor returns. I don't have one, so I don't know.

PS. Please don't cross post. If you didn't understand what I posted on http://arduino.cc/forum/index.php/topic,99709.msg748238.html, you could have said so, and I, or someone else, would have expanded on it.

[Reply #2 on:]

Sorry for reposting something similar.  How would I find out the range?

Thanks

[Reply #3 on:]

. How would I find out the range?

Write a simple sketch to print raw readings.
Point the sensor at the sky.
Point the sensor at something really close.
Point the sensor at the limits of detection.
Note the values.

[Reply #4 on:]

I'm really sorry for being new to this, but how would I write a sketch to print raw readings?

Thanks

[Reply #5 on:]

You already have one that converts the raw value to inches and centimetres. One of those options will probably be suitable.

[Reply #6 on:]

Code:

  pulse = pulseIn(pwPin, HIGH);
  //147uS per inch
  inches = pulse/147;
  //change inches to centimetres
  cm = inches * 2.54;
  Serial.print(inches);
  Serial.print("in, ");
  Serial.print(cm);
  Serial.print("cm");
  Serial.println();
  delay(500);
}

If I change that code above to this:

Code:

  pulse = pulseIn(pwPin, HIGH);
  Serial.print(pulse);
  Serial.println();
  delay(500);
}

Will that give me raw readouts?

[Reply #7 on:]

Yes, it would.

[Reply #8 on:]

Yes, and you could make the first print a println, and skip the second completely.

[Reply #9 on:]

What does 'println' do?  Can you explain it in layman's terms please?

Thanks

[Reply #10 on:]

http://arduino.cc/en/Serial/Println

[Reply #11 on:]

I have started again with this project starting from this: http://arduino.cc/en/Tutorial/Midi

I can get raw values from the MaxBotix sonar using this code:

Code:

//Feel free to use this code.
//Please be respectful by acknowledging the author in the code if you use or modify it.
//Author: Bruce Allen
//Date: 23/07/09

//Digital pin 7 for reading in the pulse width from the MaxSonar device.
//This variable is a constant because the pin will not change throughout execution of this code.

const int pwPin = 7;

//variables needed to store values

long pulse, inches, cm;


void setup() {
  //This opens up a serial connection to shoot the results back to the PC console
  Serial.begin(9600);
}


void loop() {
  pinMode(pwPin, INPUT);
    //Used to read in the pulse that is being sent by the MaxSonar device.
  //Pulse Width representation with a scale factor of 147 uS (microseconds) per Inch.

  pulse = pulseIn(pwPin, HIGH);
  Serial.println(pulse);
  delay(500);
}

I am trying to change get the raw values to map to the range 0-127 so the distance measurement can act as a note.

I have put this code together, but it does not work:

Code:

//Feel free to use this code.
//Please be respectful by acknowledging the author in the code if you use or modify it.
//Author: Bruce Allen
//Date: 23/07/09

//Digital pin 7 for reading in the pulse width from the MaxSonar device.
//This variable is a constant because the pin will not change throughout execution of this code.

const int pwPin = 7;

//variables needed to store values

byte note = 0;            // The MIDI note value to be played

long pulse;


void setup() {
  //This opens up a serial connection to shoot the results back to the PC console
  Serial.begin(31250);
}


void loop() {
  pinMode(pwPin, INPUT);
    //Used to read in the pulse that is being sent by the MaxSonar device.
  //Pulse Width representation with a scale factor of 147 uS (microseconds) per Inch.

  pulse = pulseIn(pwPin, HIGH);
  Serial.println(pulse);
  delay(500);
 
  mappedPulse = map(pulse, 827, 15000, 0, 127);  //map value to 0-127
 
}

 //  plays a MIDI note.  Doesn't check to see that
 //  cmd is greater than 127, or that data values are  less than 127:
 void noteOn(byte cmd, byte data1, byte data2) {
   Serial.write( byte(cmd) );
   Serial.write( byte(data1) );
   Serial.write( byte(data2) );
 }

Can someone PLEASE help me write it!!

[Reply #12 on:]

Once you have a mapped value, don't you think you should call noteOn()?

[Reply #13 on:]

I keep getting the error:

Code:

Final_MIDI2.cpp: In function 'void loop()':
Final_MIDI2:32: error: 'mappedPulse' was not declared in this scope

[Reply #14 on:]

Where do you actually define a type for mappedPulse?