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Topic: Trying to control motor with Ping ultrasonic sensor (Read 7000 times) previous topic - next topic


Code: [Select]
/* Ping))) Sensor

This sketch reads a PING))) ultrasonic rangefinder and returns the
distance to the closest object in range. To do this, it sends a pulse
to the sensor to initiate a reading, then listens for a pulse
to return. The length of the returning pulse is proportional to
the distance of the object from the sensor.

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


created 3 Nov 2008
by David A. Mellis
modified 30 Aug 2011
by Tom Igoe

This example code is in the public domain.


// this constant won't change. It's the pin number
// of the sensor's output:
const int pingPin = 7;

void setup() {
// initialize serial communication:

void loop()

// establish variables for duration of the ping,
// and the distance result in inches and centimeters:
long duration, inches, cm;

// 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:
pinMode(pingPin, OUTPUT);
digitalWrite(pingPin, LOW);
digitalWrite(pingPin, HIGH);
digitalWrite(pingPin, 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(pingPin, INPUT);
duration = pulseIn(pingPin, HIGH);

// convert the time into a distance
inches = microsecondsToInches(duration);
cm = microsecondsToCentimeters(duration);

if (inches > 6 ) {
analogWrite(3, 125);

digitalWrite(8, LOW);
analogWrite(11, 130);

} else if (inches <= 6){   
  analogWrite(3, 0); //Spins the motor on Channel A at full speed


Serial.print("in, ");


long microsecondsToInches(long microseconds)
// According to Parallax's datasheet for the PING))), there are
// 73.746 microseconds per inch (i.e. sound travels at 1130 feet per
// second). This gives the distance travelled by the ping, outbound
// and return, so we divide by 2 to get the distance of the obstacle.
// See: http://www.parallax.com/dl/docs/prod/acc/28015-PING-v1.3.pdf
return microseconds / 74 / 2;

long microsecondsToCentimeters(long microseconds)
// The speed of sound is 340 m/s or 29 microseconds per centimeter.
// The ping travels out and back, so to find the distance of the
// object we take half of the distance travelled.
return microseconds / 29 / 2;

The sensor will not dictate whether the engine moves or not, one engine is suppose to continually move while one stops if an object is within 6 inches....


To get help here say what the code does and also what you want it to do.
Simply posting code and letting people guess where you are having trouble is not going to work.


I thought i did at the bottom but it stayed in the box.. probably didn't put enough about it either, sorry to inconvenience you.

The code has and if statement saying that if the distance is more than 6 inches, turn both motors.
then it has an else if statement saying that if the statement is less than or equal to 6 inches, stop one motor

the motors turn the same direction until i put my hand in front of the Ping sensor and then pull it away, then only one will turn at a time.

can someone help ive tried 3 different codes for motors none of them work or they will only allow the engines to turn one direction only


You need to break it down.
Does your sensor give you reasonable values?
You find out by putting a print statement in the code and seeing what values it returns.
Then are your if statements doing the right thing? Again a print statement will tell you what part of the program you are in.
Finally is your hardware working correctly? A print statement will tell you if you have sent the code to make it move.


If i try this my sensor says only 4 inches 10 cm, when i get out the inches it says 40+ cm, so i guess something is not right.


ok its working the only problem is that i cannot switch the direction of the continually spinning motor, which i need to in the if statement can you helpme with this?


I'm sure someone could, but you'll need to provide some more detail about your hardware and how it's wired up. Your latest code, if you've changed it, would be needed too.


ok its working the only problem is that i cannot switch the direction of the continually spinning motor, which i need to in the if statement can you helpme with this?

You're going to have a really hard time controlling a bot using that sketch.  Using pulseIn is never a good idea.  You really need to move to an interrupt-driven paradigm to create projects that work in the real world.  It may take some getting used to, but it's the way to go long-term.  Instead of your current ultrasonic sensor code, you should use the NewPing library and the timer interrupt method.  There's an example sketch that shows how to use it.

Also, shift from using delay statements to timer-triggered events.  This will help you move from the "hello world" phase to a finished project.

My hardware: Arduino, Teensy 2.0, Teensy 3.2 & custom ATmega328
My libraries: NewPing, LCDBitmap, toneAC, toneAC2, NewTone, TimerFreeTone
My Projects: https://dogblocker.com & https://baconorbeer.com
My beer: Great Lakes Brewing Co. Lake Erie Monster

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