Parking Sensor problem

[mikeg291]

Just completed building the parking sensor project and interfaced it to a Vera edge via NRF2501,s and every thing works. The problem I am having is the sensor (monitoring it with serial monitor to confirm ) when a vehicle is parked it changes states ever 5 seconds from car parked to car gone . this does not occur when vehicle is actually gone . It reports correctly. I have verified connections, reloaded the sketch and now I am at a complete loss . Any suggestions .

[mfalkvidd]

Welcome @mikeg291 !
Uncomment this

//  Serial.println(fullDist);

and see what the serial output look like. That should give a clue into what is happening.

[BulldogLowell]

@mikeg291

It could be that transient sound waves are reflecting/scattering around and affecting the readings. The NewPing library states that 29milliseconds should be the shortest delay between reads.

Sound travels a little more than one foot in 1millisecond so you have an inherent delay in an empty garage; 15 feet each way, for example is about 30milliseconds from ping to read.

So, if you insert a delay(50) after you obtain the distance you may leave enough time for all of the sound to be absorbed or reflected away.

void loop()
{
  unsigned long now = millis();
  
  unsigned int fullDist = (sonar.ping_median() / US_ROUNDTRIP_CM);
//  Serial.println(fullDist);
  int displayDist = min(fullDist, MAX_DISTANCE);
  if (displayDist == 0 && skipZero<10) {
    // Try to filter zero readings
    skipZero++;
    return;
  }
  delay(50);  // try this
  // etcetera

[finch666]

@BulldogLowell said:

@mikeg291

It could be that transient sound waves are reflecting/scattering around and affecting the readings. The NewPing library states that 29milliseconds should be the shortest delay between reads.

Sound travels a little more than one foot in 1millisecond so you have an inherent delay in an empty garage; 15 feet each way, for example is about 30milliseconds from ping to read.

So, if you insert a delay(50) after you obtain the distance you may leave enough time for all of the sound to be absorbed or reflected away.

I second this. Built the sensor with a neopixel ring and the leds go berserk when I am about 3 cm away from the sensor with my hand.

[mikeg291]

Problem solved Turned out to be a bad sensor and with mfalkvidd 's suggestion troubleshooting was a lot easier . Thanks