[Need help] FEZ Panda II with HC-SR04

Archive
21

Do not use glitch filter with edge both please

22

I am not sure but I think you can’t have glitch filter on with an InterruptPort. What is the default state of the echo pin? Can you describe what does the sensor do with the echo pin once you have triggered the measurement?

Edit: Didn’t see Gus’s reply.

23

The echo pin on the HC-SRO4 goes high (simultaneous with 10 us trigger pulse) until it sees a return echo (thus the timing) and if no echo times out &goes low at about 38 ms.

24

@ idafez - Thanks! :slight_smile:

25

@ idafez -
+1

26

Guys, help!
please
it’s very important for me.

All time I find completed libraries and classes on TinyCLR, but now, for HC-SR04 I can’t do it.
I just want library, what use one function to count distance in my project

Thank you!

27

Did you try last suggestion?

28

@ Architect -
No,I don’t understand them (

29

What in particular are struggling with?

30

I have error:
An unhandled exception of type “System.ArgumentException” occurred Microsoft.SPOT.Hardware.dll
in this line:

private static InterruptPort EchoPin = new InterruptPort((Cpu.Pin)FEZ_Pin.Digital.Di10, true, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeBoth);

I don’t know how to fix it,

31

Ok you absolutely have to read the documentation. The suggestion was not to use the glitch filter. This is the second parameter in constructor which you have set to “true” effectively enabling it. Use “false” instead to disable it.

32

Oh no, again appeared error:
“An unhandled exception of type “System.ArgumentException” occurred Microsoft.SPOT.Hardware.dll”

33

Try using pull down resistor mode.

34

How I can do it?

35

Change parameter 3 from disabled to pulldown

36

Yes, it helps, but now this error appear in this line:

  EchoPin.OnInterrupt += new NativeEventHandler(port_OnInterrupt);
37

What error?

38

“An unhandled exception of type “System.ArgumentException” occurred Microsoft.SPOT.Hardware.dll”

39

I don’t have that sensor so can’t verify/adapt that code, but here is somebody implemented it for netduino. You should be able to use it:

40

I decide to use this code:

using System;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using GHIElectronics.NETMF.Hardware;
using GHIElectronics.NETMF.FEZ;

namespace sonar
{
    public class Program
    {
        private static int ticks;

        private static InterruptPort EchoPin = new InterruptPort((Cpu.Pin)FEZ_Pin.Digital.Di7, false, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeLow);
        private static OutputPort TriggerPin = new OutputPort((Cpu.Pin)FEZ_Pin.Digital.Di6, false);

        public static void Main()
        {
            EchoPin.OnInterrupt += new NativeEventHandler(EchoPin_OnInterrupt);
            EchoPin.DisableInterrupt();
            while (true)
            {
                Distance();
             //   Debug.Print("distance = " + myDistance + " mm.");
                Thread.Sleep(1000);
            }
        }

       /* private static void EchoPin_OnInterrupt(uint data1, uint data2, DateTime time)
        {
            //throw new NotImplementedException();
        }*/

        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 EchoPin_OnInterrupt(uint port, uint state, DateTime time)
        {
       
            if (state == 0) // falling edge, end of pulse
            {
              
                int pulseWidth = (int)time.Ticks - ticks;
                // valid for 20A°C
                int pulseWidthMilliSeconds = pulseWidth * 10 / 582;
                //valid for 24A°C
                //int pulseWidthMilliSeconds = (pulseWidth * 10 / (int)578.29);
                Debug.Print("Distance = " + pulseWidthMilliSeconds + " millimA?tres.");
              
            }
            else
            {
                ticks = (int)time.Ticks;
            }
            EchoPin.ClearInterrupt();
        }

    }
}

and i have next values:

Distance = -903322 millimA?tres.
Distance = -866169 millimA?tres.
Distance = -691589 millimA?tres.
Distance = -517014 millimA?tres.
Distance = -343862 millimA?tres.
Distance = -169172 millimA?tres.
Distance = 5516 millimA?tres.
Distance = 180193 millimA?tres.
Distance = 356453 millimA?tres.
Distance = 531129 millimA?tres.

This values is wrong.
Looks like time only count (inc or dec).