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Author Topic: Ping sensor to light dim/brighten  (Read 1050 times)
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Hi i'm a beginner in using Arduino programs. I've successfully merged the codes for Ping Sensor and 8 Leds
My codes allows my 8 leds to fade when far away and brighten up when closed up
However my leds stay bright even when noone is there
I've programmed it to say dim as long as 300cm but there was no change
Code:
const int pingPin = 7;
int ledPins[] = {3,5,6,9,10,11};
int brightness;
void setup() {
  brightness = 0;
  // initialize serial communication:
  Serial.begin(9600);
  for(int i = 0; i < 6; i++){         //this is a loop and will repeat eight times
  pinMode(ledPins[i],OUTPUT);
 }
}

void loop()
{
  for(int i = 0; i < 6; i++) {
  digitalWrite(ledPins[i], LOW);}

  // 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);
  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
  inches = microsecondsToInches(duration);
  cm = microsecondsToCentimeters(duration);
 
  Serial.print(inches);
  Serial.print("in, ");
  Serial.print(cm);
  Serial.print("cm");
  Serial.println();
 
  delay(5);
 
  brightness = map(cm, 300, 0, 0, 255);
    for(int i = 0; i < 6; i++) {
  analogWrite(ledPins[i], brightness);
   
}
  {
  while (cm>300)
  brightness = 0;}
  for(int i = 0; i < 6; i++) {
  analogWrite(ledPins[i], brightness);
}
}

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;
}

I'll be extremely grateful if someone can assist me to change the codes so the led lights will stay dim/off
when no one is there(By that, I mean when the Ping Sensor does not read anyone near it)
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What distance values are you getting from your serial output when there is no object in front of your sensor?

Every time through loop() you are turning the LEDs off, then setting the brightness, then setting them off again if cm>300.  That's probably overkill.

You might want to use the constrain() function before or after mapping to keep the results in the expected range:
Code:
brightness = map(constrain(cm, 0, 300), 300, 0, 0, 255);

or

 brightness = constrain(map(cm, 300, 0, 0, 255), 0, 255);
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wow thanks a lot really i appreciate it
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wow thanks a lot really i appreciate it

I would also suggest not using the ping code you're using as it has a very long delay if there's no object detected.  Instead, try using the NewPing library which will work with the Ping))) sensor.

Tim
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Arduino - Teensy - Raspberry Pi
My libraries: NewPing - LCDBitmap - toneAC - NewTone - TimerFreeTone

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