Go Down

Topic: HC-SR04 Ultrasonic Sensor to control Solenoid push rate (Read 917 times) previous topic - next topic

had this posted in the wrong topic, hopefully someone can shed some light on this project?


I am currently requiring some help with a project involving a HC-SR04 Ultrasonic Sensor to control a Solenoid so that the rate at which the solenoid is pushing against an object can be controlled by a hand movement in front of the ultrasonic sensor, ranging from about 0 (being the fastest rate) - 100cm (being the slowest rate)

So far I have gotten my code to turn an LED on when the reading in the serial monitor is between 2 and 50
hopefully you can make some sense of it:

Code: [Select]

int ledPin = 4;
int dist; //how far the object is away from the module(cm)
int val = 0;
#define trig 11
#define echo 12

void setup() {
  Serial.begin (9600);
  pinMode(echo, INPUT);
  pinMode(trig, OUTPUT);
  pinMode(ledPin, OUTPUT);


}

void loop() {
  int duration, distance;
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig, LOW);
  //receive the trigger signal echo, and calculate cm to the object
  val= pulseIn(echo, HIGH);
  dist= val/58; //converts raw to cm, valueSensor/74/2 = inches

  Serial.println(dist);
  if (dist >= 50 || dist <= 2)
  {
    digitalWrite(ledPin, LOW);
  }

  else {
digitalWrite(ledPin, HIGH);
   
  }
}


all I am wondering now is how the heck I can create a slow - fast blink rate of the LED determined by the 0-200 serial reading I am getting (if i get the LED to blink fast to slow, I can then use my ULN2003AN chip to control a solenoid to turn on and off in the same motion the LED does)

Thanks, would love some help! I hope that is enough information!  :D

AWOL

Have a look at the blink-without-delay example that is included with the IDE.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

working with this code now, I can read out the values of the ultrasonic sensor as cm
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

   http://www.arduino.cc/en/Tutorial/Ping
   
   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;
int ledPin = 13;



void setup() {
  // initialize serial communication:
  Serial.begin(9600);
}

void loop()
{
  // establish variables for duration of the ping,
  // and the distance result in inches and centimeters:
  long duration, 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);
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);
  delayMicroseconds(5);
  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

  cm = microsecondsToCentimeters(duration);
 
  Serial.print(cm);
  Serial.print("cm");
  Serial.println();
 
  delay(10);
}

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;
}


now I am wondering how i can get it to read only between 0 - 100cm , and then convert that to the blink of an LED... its strange I can only get it to work with a potentiometer, but when I try to use the Ultrasonic sensor it will not read it the same as an analog read...... I dont really understand what is going on with the blink-delay tutorial.... and how I can relate it to this as it is not an analog read..

Go Up
 


Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

Arduino
via Egeo 16
Torino, 10131
Italy