It’s not too important that we get every pulse.
I tried the following code, but still get all zeroes:
public class UltraSonicSensors 
{
        private static final int LEFT_ULTRASONIC_INPUT_PIN = 35;
        private static final int LEFT_STROBE_ULTRASONIC_OUTPUT_PIN = 15;
        private final PulseInput leftInput;
        private DigitalOutput leftStrobe;
        private float leftDistance;
        private IOIO ioio;
        
        public UltraSonicSensors(IOIO ioio) throws ConnectionLostException 
        {
                this.leftInput = ioio.openPulseInput(LEFT_ULTRASONIC_INPUT_PIN, 
PulseMode.POSITIVE);
                this.leftStrobe = 
ioio.openDigitalOutput(LEFT_STROBE_ULTRASONIC_OUTPUT_PIN);
                this.ioio = ioio;
        }

        public void read() throws ConnectionLostException, InterruptedException 
        {
                read(leftStrobe, leftInput);
        }

        private void read(DigitalOutput strobe, PulseInput input) throws 
ConnectionLostException, InterruptedException 
        {
                ioio.beginBatch();
                strobe.write(true);
                strobe.write(false);
                ioio.endBatch();
                while (true) 
                {
                  float leftDistance = leftInput.getDurationBuffered();
                  if (leftDistance > .0000001)
                  {
                          break;
                  }
                }
        }

        public float getLeftDistance() 
        {
                return leftDistance;
        }
}
What should I try next?
Thanks for the lead to the 4-pin sensors.  I have ordered some…but since a lot 
of the kids already have the 3-pin versions, I’m stuck with having to make that 
work, too.
I use use a pretty simple circuit to separate the input from the 
output…attached.

Thanks for all the great help.

On Apr 15, 2014, at 9:41 PM, Ytai Ben-Tsvi <[email protected]> wrote:

> Yes, that's what I meant when I said that you may miss the actual pulse.
> 
> What about the following approach:
> beginBatch();
> sendPulse();
> endBatch();
> while (true) {
>   float duration = pulseIn.GetDurationBuffered();
>   if (duration > MIN_DURATION) return duration;
> }
> 
> Of course, you can timeout if you want.
> With this approach, every pulse is captured and considered, and you're 
> filtering out the really short ones that indicate the input pulses.
> 
> BTW, there are equivalent ultrasonic range finders that have a more pleasant 
> interface (for example, analog, or similar to the one you have but the 
> feedback is on a separate pin). Here's one (available on DX for <$5):
> http://www.micropik.com/PDF/HCSR04.pdf
> 
> 
> 
> On Tue, Apr 15, 2014 at 7:00 PM, Vic Wintriss <[email protected]> wrote:
> Ytai:
> 
> With the sync() call after the endBatch() and before the getDuration() the 
> program hangs up and I get no readings.
> 
> Vic
> 
> On Apr 15, 2014, at 5:32 PM, Ytai Ben-Tsvi <[email protected]> wrote:
> 
>> This code doesn't have the sync() call I proposed. It should come after the 
>> batch.
>> 
>> On Apr 15, 2014 4:43 PM, "Vic Wintriss" <[email protected]> wrote:
>> Ytai:
>> 
>> This code produces only 1.6875E-5…reading 2 times per second.
>> 
>> import ioio.lib.api.DigitalOutput;
>> import ioio.lib.api.IOIO;
>> import ioio.lib.api.PulseInput;
>> import ioio.lib.api.PulseInput.PulseMode;
>> import ioio.lib.api.exception.ConnectionLostException;
>> 
>> public class UltraSonicSensors 
>> {
>>      private static final int LEFT_ULTRASONIC_INPUT_PIN = 35;
>>      private static final int LEFT_STROBE_ULTRASONIC_OUTPUT_PIN = 15;
>>      private final PulseInput leftInput;
>>      private DigitalOutput leftStrobe;
>>      private float leftDistance;
>>      private IOIO ioio;
>>      
>>      public UltraSonicSensors(IOIO ioio) throws ConnectionLostException 
>>      {
>>              this.leftInput = ioio.openPulseInput(LEFT_ULTRASONIC_INPUT_PIN, 
>> PulseMode.POSITIVE);
>>              this.leftStrobe = 
>> ioio.openDigitalOutput(LEFT_STROBE_ULTRASONIC_OUTPUT_PIN);
>>              this.ioio = ioio;
>>      }
>> 
>>      public void read() throws ConnectionLostException, InterruptedException 
>>      {
>>              read(leftStrobe, leftInput);
>>      }
>> 
>>      private void read(DigitalOutput strobe, PulseInput input) throws 
>> ConnectionLostException, InterruptedException 
>>      {
>>              ioio.beginBatch();
>>              strobe.write(true);
>>              strobe.write(false);
>>              ioio.endBatch();
>>              this.leftDistance =  input.getDurationSync();
>>      }
>> 
>>      public float getLeftDistance() 
>>      {
>>              return leftDistance;
>>      }
>> }
>> On Apr 15, 2014, at 4:27 PM, Ytai Ben-Tsvi <[email protected]> wrote:
>> 
>>> Can you send me the most "correct" version of your code that demonstrates 
>>> the issue?
>>> I can probably make the necessary changes to sync () if this is indeed a 
>>> problem.
>>> 
>>> On Apr 15, 2014 4:03 PM, "Vic Wintriss" <[email protected]> wrote:
>>> Thanks for the ideas. I've tried many combinations of synch, 
>>> readBuffered...etc, but unfortunately it still reads very small 
>>> numbers...probably measuring the last part of the trigger pulse. Is there 
>>> any way that I can delay the read by a couple of hundred micro seconds?  
>>> Could you do the..... sync() call  "send" half inside the batch and "wait" 
>>> half outside thing?
>>> 
>>> Thanks for all the help.  The kids are trying to use these sensors for 
>>> iARoC 2014 (the International Autonomous Robot Competition) here in San 
>>> Diego.
>>> 
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