troubleshooting the ping))) sensor

system · October 12, 2010, 8:56am

Hi, I'm very new to this arduino project. I used mjmcondor's code to interfaced the Ping))) sensors,http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1236272388.

int ultraSoundSignalPins[] = {2,3,4,5}; // Left,Front, Front Right, Rear Ultrasound signal pins
int farthest_Dist=ping(0);
int pinFWD=7;
int pinREAR=8;
int pinLEFT=9;
int pinRIGHT=10;[/i]

[i]void setup() {
  Serial.begin(9600);
  pinMode(pinFWD,OUTPUT);
  pinMode(pinREAR,OUTPUT);
  pinMode(pinLEFT,OUTPUT);
  pinMode(pinRIGHT,OUTPUT);[/i]

[i]unsigned long ultrasoundValue;
  for(int i=0; i < 4; i++)
  {
    ultrasoundValue = ping(i);
    Serial.print(ultrasoundValue);
    Serial.print("in, ");    
    Serial.println();
    
  }
  {
      {

    
    
     if (ping(0)==ping(1)==ping(2)==ping(3))
   {
     digitalWrite(pinLEFT,LOW);
     digitalWrite(pinFWD,LOW);
     digitalWrite(pinRIGHT,LOW);
     digitalWrite(pinREAR,LOW);
   }
   else if (ping(2)>ping(0))
     {
       farthest_Dist=ping(2);
       digitalWrite(pinRIGHT,HIGH);
         digitalWrite(pinLEFT,LOW);
     digitalWrite(pinFWD,LOW);
     digitalWrite(pinREAR,LOW);
     }
     else if (ping(3) > ping(0))
     {
       farthest_Dist=ping(3);
       digitalWrite(pinREAR,HIGH);
         digitalWrite(pinLEFT,LOW);
     digitalWrite(pinFWD,LOW);
     digitalWrite(pinRIGHT,LOW);
   }
     else if (ping(1) > ping(0))
     {
       farthest_Dist=ping(1);
       digitalWrite(pinFWD,HIGH);
       digitalWrite(pinLEFT,LOW);
       digitalWrite(pinRIGHT,LOW);
       digitalWrite(pinREAR,LOW);
     }
     else
     {
       farthest_Dist = ping(0);
       digitalWrite(pinLEFT,HIGH);
     digitalWrite(pinFWD,LOW);
     digitalWrite(pinRIGHT,LOW);
     digitalWrite(pinREAR,LOW);
   }

Serial.print (farthest_Dist);
    Serial.println();
    }
  }
  
}



//Ping function
unsigned long ping(int i)
{
  unsigned long echo;

  pinMode(ultraSoundSignalPins[i], OUTPUT); // Switch signalpin to output
  digitalWrite(ultraSoundSignalPins[i], LOW); // Send low pulse
  delayMicroseconds(2); // Wait for 2 microseconds
  digitalWrite(ultraSoundSignalPins[i], HIGH); // Send high pulse
  delayMicroseconds(5); // Wait for 5 microseconds
  digitalWrite(ultraSoundSignalPins[i], LOW); // Holdoff
  pinMode(ultraSoundSignalPins[i], INPUT); // Switch signalpin to input
  digitalWrite(ultraSoundSignalPins[i], HIGH); // Turn on pullup resistor
  echo = pulseIn(ultraSoundSignalPins[i], HIGH); //Listen for echo
  return (echo / 58.138) * .39; //convert to CM then to inches

However, I got the following errors.

AeroQuad2.cpp: In function 'long unsigned int ping(int)':
Eeprom:24: error: a function-definition is not allowed here before '{' token
float readFloat(int address) 
{
  union floatStore {
    byte floatByte[4];
    float floatVal;
  } floatOut;
  
  for (int i = 0; i < 4; i++) 
    floatOut.floatByte[i] = EEPROM.read(address + i);
  return floatOut.floatVal;
}

Can someone tell me where I went wrong?

Thanks.

system · October 12, 2010, 9:31am

Strange. I copied the the second of your code snippets into one of my .pde files and it works without a problem. I just had to #include <EEPROM.h>, but I guess you do that too.

Korman

system · October 13, 2010, 5:30am

The second code works fine on its own. However, after adding the first code into the whole program then the errors come about. Is there something else which i have not done?

cr0sh · October 13, 2010, 5:51am

Can someone tell me where I went wrong?

Using "crap" code?

Here's the whole code after I cleaned it up (there were like missing braces, out of place braces, a missing loop() definition, etc):

#include <EEPROM.h>

int ultraSoundSignalPins[] = {2,3,4,5}; // Left,Front, Front Right, Rear Ultrasound signal pins
int farthest_Dist=ping(0);
int pinFWD=7;
int pinREAR=8;
int pinLEFT=9;
int pinRIGHT=10;

void setup() {
  Serial.begin(9600);
  pinMode(pinFWD,OUTPUT);
  pinMode(pinREAR,OUTPUT);
  pinMode(pinLEFT,OUTPUT);
  pinMode(pinRIGHT,OUTPUT);

  unsigned long ultrasoundValue;
  
  for(int i=0; i < 4; i++) {
    ultrasoundValue = ping(i);
    Serial.print(ultrasoundValue);
    Serial.print("in, ");    
    Serial.println();    
  }
    
  if (ping(0)==ping(1)==ping(2)==ping(3)) {
    digitalWrite(pinLEFT,LOW);
    digitalWrite(pinFWD,LOW);
    digitalWrite(pinRIGHT,LOW);
    digitalWrite(pinREAR,LOW);
  }
  else if (ping(2)>ping(0)) {
    farthest_Dist=ping(2);
    digitalWrite(pinRIGHT,HIGH);
    digitalWrite(pinLEFT,LOW);
    digitalWrite(pinFWD,LOW);
    digitalWrite(pinREAR,LOW);
  }
  else if (ping(3) > ping(0)) {
    farthest_Dist=ping(3);
    digitalWrite(pinREAR,HIGH);
    digitalWrite(pinLEFT,LOW);
    digitalWrite(pinFWD,LOW);
    digitalWrite(pinRIGHT,LOW);
  }
  else if (ping(1) > ping(0)) {
    farthest_Dist=ping(1);
    digitalWrite(pinFWD,HIGH);
    digitalWrite(pinLEFT,LOW);
    digitalWrite(pinRIGHT,LOW);
    digitalWrite(pinREAR,LOW);
  }
  else {
    farthest_Dist = ping(0);
    digitalWrite(pinLEFT,HIGH);
    digitalWrite(pinFWD,LOW);
    digitalWrite(pinRIGHT,LOW);
    digitalWrite(pinREAR,LOW);
  }

  Serial.print (farthest_Dist);
  Serial.println();
}

void loop() {
}

//Ping function
unsigned long ping(int i)
{
  unsigned long echo;

  pinMode(ultraSoundSignalPins[i], OUTPUT); // Switch signalpin to output
  digitalWrite(ultraSoundSignalPins[i], LOW); // Send low pulse
  delayMicroseconds(2); // Wait for 2 microseconds
  digitalWrite(ultraSoundSignalPins[i], HIGH); // Send high pulse
  delayMicroseconds(5); // Wait for 5 microseconds
  digitalWrite(ultraSoundSignalPins[i], LOW); // Holdoff
  pinMode(ultraSoundSignalPins[i], INPUT); // Switch signalpin to input
  digitalWrite(ultraSoundSignalPins[i], HIGH); // Turn on pullup resistor
  echo = pulseIn(ultraSoundSignalPins[i], HIGH); //Listen for echo
  return (echo / 58.138) * .39; //convert to CM then to inches 
}

float readFloat(int address)
{
  union floatStore {
    byte floatByte[4];
    float floatVal;
  } floatOut;
  
  for (int i = 0; i < 4; i++) {
    floatOut.floatByte[i] = EEPROM.read(address + i);
  }
  
  return floatOut.floatVal;
}

This seems to compile fine under 0019; I don't know where the extra characters came from, or why stuff was missing - but as a case of "copypasta programming" it left a lot to be desired. Also note that I cannot vouch that the code above will run as expected (I am curious why all the code is in setup, and nothing in loop()?) - just that this compiles without error...

Hmm - looking at the code from your first link, here's what the code should -probably- look like (ignore the code above):

#include <EEPROM.h>

int ultraSoundSignalPins[] = {2,3,4,5}; // Left,Front, Front Right, Rear Ultrasound signal pins
int farthest_Dist=ping(0);
int pinFWD=7;
int pinREAR=8;
int pinLEFT=9;
int pinRIGHT=10;

void setup() {
  Serial.begin(9600);
  pinMode(pinFWD,OUTPUT);
  pinMode(pinREAR,OUTPUT);
  pinMode(pinLEFT,OUTPUT);
  pinMode(pinRIGHT,OUTPUT);
}

void loop() {

  unsigned long ultrasoundValue;
  
  for(int i=0; i < 4; i++) {
    ultrasoundValue = ping(i);
    Serial.print(ultrasoundValue);
    Serial.print("in, ");    
    Serial.println();    
  }
    
  if (ping(0)==ping(1)==ping(2)==ping(3)) {
    digitalWrite(pinLEFT,LOW);
    digitalWrite(pinFWD,LOW);
    digitalWrite(pinRIGHT,LOW);
    digitalWrite(pinREAR,LOW);
  }
  else if (ping(2)>ping(0)) {
    farthest_Dist=ping(2);
    digitalWrite(pinRIGHT,HIGH);
    digitalWrite(pinLEFT,LOW);
    digitalWrite(pinFWD,LOW);
    digitalWrite(pinREAR,LOW);
  }
  else if (ping(3) > ping(0)) {
    farthest_Dist=ping(3);
    digitalWrite(pinREAR,HIGH);
    digitalWrite(pinLEFT,LOW);
    digitalWrite(pinFWD,LOW);
    digitalWrite(pinRIGHT,LOW);
  }
  else if (ping(1) > ping(0)) {
    farthest_Dist=ping(1);
    digitalWrite(pinFWD,HIGH);
    digitalWrite(pinLEFT,LOW);
    digitalWrite(pinRIGHT,LOW);
    digitalWrite(pinREAR,LOW);
  }
  else {
    farthest_Dist = ping(0);
    digitalWrite(pinLEFT,HIGH);
    digitalWrite(pinFWD,LOW);
    digitalWrite(pinRIGHT,LOW);
    digitalWrite(pinREAR,LOW);
  }

  Serial.print (farthest_Dist);
  Serial.println();
}

//Ping function
unsigned long ping(int i)
{
  unsigned long echo;

  pinMode(ultraSoundSignalPins[i], OUTPUT); // Switch signalpin to output
  digitalWrite(ultraSoundSignalPins[i], LOW); // Send low pulse
  delayMicroseconds(2); // Wait for 2 microseconds
  digitalWrite(ultraSoundSignalPins[i], HIGH); // Send high pulse
  delayMicroseconds(5); // Wait for 5 microseconds
  digitalWrite(ultraSoundSignalPins[i], LOW); // Holdoff
  pinMode(ultraSoundSignalPins[i], INPUT); // Switch signalpin to input
  digitalWrite(ultraSoundSignalPins[i], HIGH); // Turn on pullup resistor
  echo = pulseIn(ultraSoundSignalPins[i], HIGH); //Listen for echo
  return (echo / 58.138) * .39; //convert to CM then to inches 
}

float readFloat(int address)
{
  union floatStore {
    byte floatByte[4];
    float floatVal;
  } floatOut;
  
  for (int i = 0; i < 4; i++) {
    floatOut.floatByte[i] = EEPROM.read(address + i);
  }
  
  return floatOut.floatVal;
}

Once again - pure guesswork, but it does compile...

cr0sh · October 13, 2010, 5:57am

Something else -all- Arduino newbies should note: Do you notice something different between the code I posted and the OP's post?

Not to rag on the OP, but to point out a truism: Structured code is maintainable code.

Keep the structure of your code consistent (as you can see, I am partial to K&R styling); keep your statements aligned, orderly, and neat - and you will be able to spot errors (before and after compiling) much more quickly than you would otherwise. Proper structure also promotes readability.

If you copy-n-paste code examples that aren't structured - structure them after you paste them; for all you know, the author left in a bug or inadvertently caused one when they pasted it on their site (as I suspect is what happened to the OP here, when he cut-n-pasted from the example in the other thread). By doing so, you may spot an issue before it becomes a problem (that doesn't necessarily mean you'll be able to fix it, but it may help after the compiler throws a flag).

system · October 13, 2010, 7:08am

I am actually building an aeroquad to avoid obstacles from 4 sides using the PING ultrasonic sensors hence the above codes. I got the main codes from:
http://code.google.com/p/aeroquad/downloads/detail?name=AeroQuad_v1.7.1.zip&can=2&q=

However, the source codes i got from aeroquad seems a little complicating for a newbie like me. Is it possible to enlighten me on how to interface the sensors if i am aiming to make the quad move away from the object of concern?

system · October 13, 2010, 8:22am

That code is pretty basic, albeit not very pretty. What's readFloat used for? It's never called from what I can see. Also what's the deal with the sensor pins in an array? The array makes the rest of the code less readable - self-documenting by use of sensible variable names helps immensely

A few minor changes (and comments!) in the code would go along way to unfolding its mysteries... this compiles but I can't vouch for the functionality.

int farthest_Dist = 0;

// Left, Front, Right, Rear Ultrasound signal pins
int pinLEFT_SENSOR = 2;
int pinFRONT_SENSOR = 3;
int pinRIGHT_SENSOR = 4;
int pinREAR_SENSOR = 5;

// I'm guessing these are pins for 4 motors...
int pinFWD = 7;
int pinREAR = 8;
int pinLEFT = 9;
int pinRIGHT = 10;

void setup()
{
  Serial.begin( 9600 );
  pinMode( pinFWD, OUTPUT );
  pinMode( pinREAR, OUTPUT );
  pinMode( pinLEFT, OUTPUT );
  pinMode( pinRIGHT, OUTPUT );
}

void loop()
{
  unsigned long left, front, right, rear;

  // retrieve the distance from each sensor - does this take into account the round-trip nature of the measurement?
  left = ping( pinLEFT_SENSOR );
  front = ping( pinFRONT_SENSOR );
  right = ping( pinRIGHT_SENSOR );
  rear = ping( pinREAR_SENSOR );

  // display the retrieved distances
  Serial.print( left );
  Serial.println( "in, " );
  Serial.print( front );
  Serial.println( "in, " );
  Serial.print( right );
  Serial.println( "in, " );
  Serial.print( rear );
  Serial.println( "in, " );

  // determine which way to head based on the relative distances recorded
  if ( left == front == right == rear )
  {
    // equal distances all around - stay put
    digitalWrite( pinLEFT, LOW );
    digitalWrite( pinFWD, LOW );
    digitalWrite( pinRIGHT, LOW );
    digitalWrite( pinREAR, LOW );
  }
  else if ( right > left )
  {
    // more space to the right - head that way
    farthest_Dist = right;
    digitalWrite( pinRIGHT, HIGH );
    digitalWrite( pinLEFT, LOW );
    digitalWrite( pinFWD, LOW );
    digitalWrite( pinREAR, LOW );
  }
  else if ( rear > left )
  {
    // more space to the rear - head that way
    farthest_Dist = rear;
    digitalWrite( pinREAR, HIGH );
    digitalWrite( pinLEFT, LOW );
    digitalWrite( pinFWD, LOW );
    digitalWrite( pinRIGHT, LOW );
  }
  else if ( front > left )
  {
    // more space to the front - head that way
    farthest_Dist = front;
    digitalWrite( pinFWD, HIGH );
    digitalWrite( pinLEFT, LOW );
    digitalWrite( pinRIGHT, LOW );
    digitalWrite( pinREAR, LOW );
  }
  else
  {
    // left it is then
    farthest_Dist = left;
    digitalWrite( pinLEFT, HIGH );
    digitalWrite( pinFWD, LOW );
    digitalWrite( pinRIGHT, LOW );
    digitalWrite( pinREAR, LOW );
  }

  // display the largest distance just measured
  Serial.println( farthest_Dist );
}

// Ping function
unsigned long ping( int pin )
{
  unsigned long echo;

  pinMode( pin, OUTPUT ); // Switch signalpin to output
  digitalWrite( pin, LOW ); // Send low pulse
  delayMicroseconds( 2 ); // Wait for 2 microseconds
  digitalWrite( pin, HIGH ); // Send high pulse
  delayMicroseconds( 5 ); // Wait for 5 microseconds
  digitalWrite( pin, LOW ); // Holdoff
  pinMode( pin, INPUT ); // Switch signalpin to input
  digitalWrite( pin, HIGH ); // Turn on pullup resistor
  echo = pulseIn( pin, HIGH ); //Listen for echo
  return ( echo / 58.138 ) * .39; //convert to CM then to inches
}

Just my $0.02 worth...

G.

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