Integrating ultrasonic sensors with Raspberry pi using c#

0 votes

I'm trying to read the distance from an ultrasonic sensor (HC-SR04) but the only values I get is 0 and 265.xx.

I am using an Raspberry Pi 2 with Windows 10 IoT Core installed.

I've written the code in C#.

This is the ultrasonic sensor class:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Diagnostics;
using Windows.Devices.Gpio;

namespace RaspberryPi
{
    class UcSensor
    {
        GpioController gpio = GpioController.GetDefault();

        GpioPin TriggerPin;
        GpioPin EchoPin;

        //Contructor
        public UcSensor(int TriggerPin, int EchoPin)
        {
            //Setting up gpio pin's
            this.TriggerPin = gpio.OpenPin(TriggerPin);
            this.EchoPin = gpio.OpenPin(EchoPin);

            this.TriggerPin.SetDriveMode(GpioPinDriveMode.Output);
            this.EchoPin.SetDriveMode(GpioPinDriveMode.Input);

            this.TriggerPin.Write(GpioPinValue.Low);
        }

        public double GetDistance()
        {
            ManualResetEvent mre = new ManualResetEvent(false);
            mre.WaitOne(500);

            //Send pulse
            this.TriggerPin.Write(GpioPinValue.High);
            mre.WaitOne(TimeSpan.FromMilliseconds(0.01));
            this.TriggerPin.Write(GpioPinValue.Low);

            //Recieve pusle
            while (this.EchoPin.Read() == GpioPinValue.Low)
            {
            }
            DateTime start = DateTime.Now;

            while (this.EchoPin.Read() == GpioPinValue.High)
            {
            }
            DateTime stop = DateTime.Now;

            //Calculating distance
            double timeBetween = (stop - start).TotalSeconds;
            double distance = timeBetween * 17000;

            return distance;
        }

    }
}

I've also written a script in python to read the values from the ultrasonic sensor and then it works but in c# I can't get it working.

At the bottom you can find the debug log:

'BACKGROUNDTASKHOST.EXE' (CoreCLR: DefaultDomain): Loaded 'C:\Program Files\WindowsApps\Microsoft.NET.CoreRuntime.1.0_1.0.22816.1_arm__8wekyb3d8bbwe\mscorlib.ni.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. 'BACKGROUNDTASKHOST.EXE' (CoreCLR: CoreCLR_UAP_Domain): Loaded 'C:\Users\DefaultAccount\AppData\Local\DevelopmentFiles\RaspiCarVS.Debug_ARM.chris\RaspiCar.winmd'. Symbols loaded. 'BACKGROUNDTASKHOST.EXE' (CoreCLR: CoreCLR_UAP_Domain): Loaded 'C:\Users\DefaultAccount\AppData\Local\DevelopmentFiles\RaspiCarVS.Debug_ARM.chris\System.Runtime.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. 'BACKGROUNDTASKHOST.EXE' (CoreCLR: CoreCLR_UAP_Domain): Loaded 'C:\Users\DefaultAccount\AppData\Local\DevelopmentFiles\RaspiCarVS.Debug_ARM.chris\WinMetadata\Windows.winmd'. Module was built without symbols. 'BACKGROUNDTASKHOST.EXE' (CoreCLR: CoreCLR_UAP_Domain): Loaded 'C:\Users\DefaultAccount\AppData\Local\DevelopmentFiles\RaspiCarVS.Debug_ARM.chris\System.Runtime.InteropServices.WindowsRuntime.dll'. Module was built without symbols. 'BACKGROUNDTASKHOST.EXE' (CoreCLR: CoreCLR_UAP_Domain): Loaded 'C:\Users\DefaultAccount\AppData\Local\DevelopmentFiles\RaspiCarVS.Debug_ARM.chris\System.Threading.dll'. Module was built without symbols. 'BACKGROUNDTASKHOST.EXE' (CoreCLR: CoreCLR_UAP_Domain): Loaded 'C:\Users\DefaultAccount\AppData\Local\DevelopmentFiles\RaspiCarVS.Debug_ARM.chris\System.Diagnostics.Debug.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. 'BACKGROUNDTASKHOST.EXE' (CoreCLR: CoreCLR_UAP_Domain): Loaded 'C:\Users\DefaultAccount\AppData\Local\DevelopmentFiles\RaspiCarVS.Debug_ARM.chris\System.Runtime.WindowsRuntime.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. Distance: 265.7457 Distance: 0 Distance: 0 Distance: 0 The program '[2508] BACKGROUNDTASKHOST.EXE' has exited with code 0 (0x0).

Oct 3, 2018 in IoT (Internet of Things) by Matt
• 2,260 points
186 views

1 answer to this question.

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0 votes

DateTime is the problem You should use the stopwatch class and it will work.The working class:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Diagnostics;
using Windows.Devices.Gpio;

namespace RaspberryPi
{
    class UcSensor
    {
        GpioController gpio = GpioController.GetDefault();

        GpioPin TriggerPin;
        GpioPin EchoPin;

        public UcSensor(int TriggerPin, int EchoPin)
        {
            this.TriggerPin = gpio.OpenPin(TriggerPin);
            this.EchoPin = gpio.OpenPin(EchoPin);

            this.TriggerPin.SetDriveMode(GpioPinDriveMode.Output);
            this.EchoPin.SetDriveMode(GpioPinDriveMode.Input);

            this.TriggerPin.Write(GpioPinValue.Low);
        }

        public double GetDistance()
        {
            ManualResetEvent mre = new ManualResetEvent(false);
            mre.WaitOne(500);
            Stopwatch pulseLength = new Stopwatch();

            //Send pulse
            this.TriggerPin.Write(GpioPinValue.High);
            mre.WaitOne(TimeSpan.FromMilliseconds(0.01));
            this.TriggerPin.Write(GpioPinValue.Low);

            //Recieve pusle
            while (this.EchoPin.Read() == GpioPinValue.Low)
            {
            }
            pulseLength.Start();


            while (this.EchoPin.Read() == GpioPinValue.High)
            {
            }
            pulseLength.Stop();

            //Calculating distance
            TimeSpan timeBetween = pulseLength.Elapsed;
            Debug.WriteLine(timeBetween.ToString());
            double distance = timeBetween.TotalSeconds * 17000;

            return distance;
        }

    }
}

answered Oct 3, 2018 by anonymous2
• 4,260 points

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