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HC-SR04 Ultrasonic Sensor Memory Problem

HC-SR04 Ultrasonic Sensor Memory

Best Answer Heroduino , 16 July 2013 - 08:06 AM

Hello Grant,

 

sorry. I had no try this. The other way is, before you return from Read() is clear the eventhandler

public static int Read(){   EchoPin.OnInterrupt += new NativeEventHandler(port_OnInterrupt);      EchoPin.DisableInterrupt();                         Distance();   Thread.Sleep(25);   EchoPin.OnInterrupt -= new NativeEventHandler(port_OnInterrupt);   return uDistance;}

Or you write a methode for allocate one time only the event handler.

 

Other Example

public static void SetEventInterupt(){      EchoPin.OnInterrupt += new NativeEventHandler(port_OnInterrupt);}public static int Read(){  EchoPin.DisableInterrupt();                         Distance();  Thread.Sleep(25);  return uDistance; }

And your main 'while' you write:

SetEventInterupt();while (true) {       lcd.Move(2, 0);       lcd.Show(Sonic.Read().ToString() + "cm ");       Thread.Sleep(1000); }

Or look on my blog and Translate my content. Well, I posted a example code. ^_^

http://meineweltinme...m-netduino.html

 

Heroduino

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#1 stotech

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Posted 16 July 2013 - 03:08 AM

Hi everyone,

 

I got some code that is working fantastic. But i found it on the forums and i don't really understand it completely. After running once a second for about twenty minutes my N+2 runs out of  memory though. I think it gets to big a queue up of interrupts built up. That's what i guess from this thread.

I really need to poll this sensor at, at least 1 Hz but preferably 2 or 4. But it runs out of memory. Can someone suggest changes to the code to allow for this. Like I said earlier, It is otherwise perfect.

 

Here is the class.

using System;using System.Threading;using Microsoft.SPOT;using Microsoft.SPOT.Hardware;using SecretLabs.NETMF.Hardware;using SecretLabs.NETMF.Hardware.Netduino;namespace Pulsator{    public class Sonic    {        public static int uDistance;        private static int ticks;        private static InterruptPort EchoPin = new InterruptPort(Pins.GPIO_PIN_D2, true, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeBoth);        private static OutputPort TriggerPin = new OutputPort(Pins.GPIO_PIN_D1, false);        public static int Read()        {            EchoPin.OnInterrupt += new NativeEventHandler(port_OnInterrupt);            EchoPin.DisableInterrupt();                                      Distance();                //Debug.Print("distance = " + myDistance + " mm.");                Thread.Sleep(25);                return uDistance;        }        public static void Distance()        {            EchoPin.EnableInterrupt();            TriggerPin.Write(false);            Thread.Sleep(2);            TriggerPin.Write(true);            Thread.Sleep(10);            TriggerPin.Write(false);            Thread.Sleep(2);        }        private static void port_OnInterrupt(uint port, uint state, DateTime time)        {            if (state == 0) // falling edge, end of pulse            {                int pulseWidth = (int)time.Ticks - ticks;                // valid for 20°C                //int pulseWidthMilliSeconds = pulseWidth * 10 / 582;                //valid for 24°C                int pulseWidthMilliSeconds = (pulseWidth * 1 / (int)578.29); //change 1 to 10 for mm                //Debug.Print("Distance = " + pulseWidthMilliSeconds.ToString() + " millimètres.");                uDistance = pulseWidthMilliSeconds;            }            else            {                ticks = (int)time.Ticks;            }            EchoPin.ClearInterrupt();        }    }}

Here is how I call it.

            while (true)            {                lcd.Move(2, 0);                lcd.Show(Sonic.Read().ToString() + "cm ");                Thread.Sleep(1000);            }

Thanks in advance.



#2 Heroduino

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Posted 16 July 2013 - 05:00 AM

Hello Grant,

 

if you used the Read() method, you allocate each time a new Event, but it dont clear it. Try this to the Methode.

public static int Read(){   if(EchoPin.OnInterrupt == null)   {      EchoPin.OnInterrupt += new NativeEventHandler(port_OnInterrupt);   }   EchoPin.DisableInterrupt();                         Distance();   //Debug.Print("distance = " + myDistance + " mm.");   Thread.Sleep(25);   return uDistance;}

Heroduino



#3 stotech

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Posted 16 July 2013 - 06:49 AM

Thanks for the quick reply. I thought it was going to work but the first oninterrupt underlines and the error is

 

"the event 'microsoft.spot.hardware.nativeeventdispatcher.oninterupt can only appear on the left hand side of += or -="

 

if i change it to +=. it says that it can't convert void to bool?

 

Any other idea's. I'm way over my head?



#4 Heroduino

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Posted 16 July 2013 - 08:06 AM   Best Answer

Hello Grant,

 

sorry. I had no try this. The other way is, before you return from Read() is clear the eventhandler

public static int Read(){   EchoPin.OnInterrupt += new NativeEventHandler(port_OnInterrupt);      EchoPin.DisableInterrupt();                         Distance();   Thread.Sleep(25);   EchoPin.OnInterrupt -= new NativeEventHandler(port_OnInterrupt);   return uDistance;}

Or you write a methode for allocate one time only the event handler.

 

Other Example

public static void SetEventInterupt(){      EchoPin.OnInterrupt += new NativeEventHandler(port_OnInterrupt);}public static int Read(){  EchoPin.DisableInterrupt();                         Distance();  Thread.Sleep(25);  return uDistance; }

And your main 'while' you write:

SetEventInterupt();while (true) {       lcd.Move(2, 0);       lcd.Show(Sonic.Read().ToString() + "cm ");       Thread.Sleep(1000); }

Or look on my blog and Translate my content. Well, I posted a example code. ^_^

http://meineweltinme...m-netduino.html

 

Heroduino



#5 stotech

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Posted 16 July 2013 - 11:18 AM

Thanks Heaps. You live up to your name. I'm very grateful.



#6 chevi99

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Posted 15 June 2014 - 10:27 PM

pls debug.print does not work. I don't know why because it doesn't give me any error and nothing happens too when i run the program







Also tagged with one or more of these keywords: HC-SR04, Ultrasonic, Sensor, Memory

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