故障使用.net micro fw轮询超声波传感器的脉冲宽度

时间：2014-05-31 07:04:05

标签： c# microcontroller .net-micro-framework netduino

我正在关注使用Parallax Ping传感器连接C＃和.net微框架的众多示例之一。

视差
http://learn.parallax.com/KickStart/28015

教程1
https://www.ghielectronics.com/community/codeshare/entry/123

教程2
http://forums.netduino.com/index.php?/topic/1721-parallax-ping-ultrasonic-sensor/

我的传感器正确连接到我的netduino plus＆＃39; 5v输出，接地和gpio 0.（我尝试过不同的端口，但结果仍然相同。

我遇到的问题是我的程序检测到高脉冲但从未检测到脉冲的低电平。它会停留在每个教程中的第二个while（while）循环中。此外，我的视差LED似乎仍然存在，并且根据文档记录它应该在每次ping爆发时发出脉冲，而不是无限期地停留。我使用了MS.SPOT.CPU.GPIO0以及SecretLabs Pins.GPIOD0枚举。秘密实验室引脚产生一个闪烁的LED，从不退出第一个while（真）循环，而MS.SPOT端口产生一个永远不会退出第二个while（真）循环的LED灯。这是我在MF编程的第一天。任何人都可以帮我指出可能存在的问题吗？

Wiring

动态视频https://dl.dropboxusercontent.com/u/62170850/20140606_153029.mp4

看起来我连接到引脚10和13，但我不是。这个角度有误导性。事实上我已经插入了Gnd和11 

using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using SecretLabs.NETMF.Hardware;
using SecretLabs.NETMF.Hardware.NetduinoPlus;
using Micro_Base_Lib;

namespace Parallax_Ping_Distance_Calculator
{
public class Program
{
    private static OutputPort onboardLed;
    private static InterruptPort onboardButton;
    public static void Main()
    {
        // write your code here
        //Cpu.GlitchFilterTime = new TimeSpan(0, 0, 0, 0, 5); //5 ms glitch filter

        onboardButton = new InterruptPort(Pins.ONBOARD_SW1, true, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeLevelHigh);

        onboardButton.OnInterrupt += new NativeEventHandler(onboardButton_OnInterrupt);

        onboardLed = new OutputPort(Pins.ONBOARD_LED, false); //initial state off


        //go into powersave mode.
        Thread.Sleep(Timeout.Infinite);

    }

    static void onboardButton_OnInterrupt(uint data1, uint data2, DateTime time)
    {
        onboardLed.Write(true);
        onboardButton.ClearInterrupt();
        Ping myPinger = new Ping(SecretLabs.NETMF.Hardware.NetduinoPlus.Pins.GPIO_PIN_D11);
        var dist = myPinger.GetDistance();

        var convertedDistance = myPinger.Convert(dist, DistanceUnits.cm);
        onboardLed.Write(false);
    }

}



    public enum DistanceUnits
    {
        mm,
        cm,
        dm,
        m,
        feet,
        inch,
        yard
    }

    public class Ping
    {
        TristatePort _port;
        DistanceUnits _unit = DistanceUnits.mm;

        double _soundSpeed = 343, _convertion = (10000 / 343) * 2; // default values

        public Ping(Cpu.Pin pin)
        {

            _port = new TristatePort(pin, false, false, ResistorModes.Disabled);
        }

        /// <summary>
        /// Automaticly adjust the convertion factor depending on air temperature.
        /// </summary>
        /// <param name="degC">The temperature in degrees celsius</param>
        public void AdjustSoundSpeed(double degC)
        {
            /* Speed of Sound (at 20 degrees celsius): 343 m/s
             * or
             * _soundSpeed = 331.4 + 0.6 * degC
             * 
             * There are 10,000,000 ticks per second.
             * 10,000,000 / _soundSpeed * 1000 can be simplyfied into:
             * 10,000 / _soundSpeed
             * times it by 2 because of round trip
             * then you get about 58.309 ticks per mm
             * 
             * then multiply if other unit is needed
             * 
             */
            _soundSpeed = 331.4 + 0.6 * degC;
            _convertion = (10000 / _soundSpeed) * 2;
        }

        private void WriteToLog(string s)
        {
            Debug.Print(DateTime.Now.ToString() + " : " + s);
        }
        /// <summary>
        /// Return the Ping))) sensor's reading in millimeters.
        /// </summary>
        /// <param name="usedefault">Set true to return value in the unit specified by the "Unit" property.
        /// Set false to return value in mm.</param>
        public double GetDistance()
        {
            bool lineState = false;
            long t1, t2;

            // Set it to an output

            if (!_port.Active) 
            _port.Active = true;
            WriteToLog("Port is in output mode");
            WriteToLog(_port.Id + " : " + "Mode: " + (_port.Active == true ? "Output" : "Input"));
            WriteToLog(_port.Id + " : " + "Read: " + _port.Read());

            //10 micro seconds is long enough for the parallax microphone to pick up a a ping.
            //http://www.parallax.com/sites/default/files/downloads/28015-PING-Detect-Distance.pdf - figure 3
            WriteToLog(_port.Id + " : " + "Mode: " + (_port.Active == true ? "Output" : "Input"));
            WriteToLog(_port.Id + " : " + "Read: " + _port.Read());
            _port.Write(true); //turns the port to high 3.3v
            WriteToLog("Signal pulse started");
            WriteToLog(_port.Id + " : " + "Mode: " + (_port.Active == true ? "Output" : "Input"));
            WriteToLog(_port.Id + " : " + "Read: " + _port.Read());
            _port.Write(false); //turns the port to low 0v
            WriteToLog("Signal pulse ended");
            WriteToLog(_port.Id + " : " + "Mode: " + (_port.Active == true ? "Output" : "Input"));
            WriteToLog(_port.Id + " : " + "Read: " + _port.Read());

            // Set port it as an input to pick up sound
            _port.Active = false;
            WriteToLog("Port is in input mode");
            WriteToLog(_port.Id + " : " + "Mode: " + (_port.Active == true ? "Output" : "Input"));
            WriteToLog(_port.Id + " : " + "Read: " + _port.Read());
            //wait for linestate to change to true. indicating the start of the pulse
            WriteToLog("Waiting for line state to turn to true.");
            while (lineState == false)
            {

                lineState = _port.Read();
                WriteToLog(_port.Id + " : " + "Mode: " + (_port.Active == true ? "Output" : "Input"));
                WriteToLog(_port.Id + " : " + "Read: " + _port.Read());
            }

            t1 = System.DateTime.Now.Ticks;
            WriteToLog("Line state reached high at : " + t1.ToString());

            WriteToLog("Waiting for line state to turn to false.");
            //wait for linestate to change to false. indicating the end of the pulse
            while (lineState == true)
            {

                lineState = _port.Read();
                WriteToLog(_port.Id + " : " + "Mode: " + (_port.Active == true ? "Output" : "Input"));
                WriteToLog(_port.Id + " : " + "Read: " + _port.Read());
            }
            t2 = System.DateTime.Now.Ticks;
            WriteToLog("Line state reached low at : " + t1.ToString());
            return Convert(((t2 - t1) / _convertion), _unit);
        }

        /// <summary>
        /// Convert the millimeters into other units.
        /// </summary>
        /// <param name="millimeters">The Ping))) sensor's mm reading.</param>
        /// <param name="outputUnit">The desired output unit.</param>
        public double Convert(double millimeters, DistanceUnits outputUnit)
        {
            double result = millimeters;

            switch (outputUnit)
            {
                case DistanceUnits.cm:
                    result = millimeters * 0.1F;
                    break;
                case DistanceUnits.dm:
                    result = millimeters * 0.01F;
                    break;
                case DistanceUnits.m:
                    result = millimeters * 0.001F;
                    break;
                case DistanceUnits.inch:
                    result = millimeters * 0.0393700787;
                    break;
                case DistanceUnits.feet:
                    result = millimeters * 0.0032808399;
                    break;
                case DistanceUnits.yard:
                    result = millimeters * 0.0010936133;
                    break;
            }

            return result;
        }

        public DistanceUnits Unit
        {
            get { return _unit; }
            set { _unit = value; }
        }
    }

}

06/01/2011 00:00:34：端口处于输出模式
06/01/2011 00:00:34:17：模式：输出
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输出
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34：信号脉冲开始了 06/01/2011 00:00:34:17：模式：输出
06/01/2011 00:00:34:17：阅读：真实 06/01/2011 00:00:34：信号脉冲结束
06/01/2011 00:00:34:17：模式：输出
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34：端口处于输入模式
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34：等待线路状态转为真 06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:34:17：模式：输入
06/01/2011 00:00:34:17：阅读：错误
06/01/2011 00:00:35:17：模式：输入

4 个答案:

答案 0 :(得分：1)

我在我的NetDuino Plus上实现了你的代码，经过一些黑客攻击（我没有像你那样拥有完全相同的传感器，所以我不得不稍微修改你的代码）这一切似乎都运行得很好。因此，我注意到你正在使用

代码的后续跟踪 
Cpu.Pin.GPIO_Pin0

就像我用

写的旧习惯一样 
Pins.GPIO_PIN_D0

你看到Cpu.Pin指的是实际的mCPU引脚为Pins.GPIO_PIN_D *引用NetDuino开发板上的引脚输出。

所以改变

Cpu.Pin.GPIO_Pin0

要

Pins.GPIO_PIN_D0

这应该可以解决你问题中提到的问题。

答案 1 :(得分：1)

技巧是它不是真正的回声信号，它是表示返回的回声的定时信号。实际上我认为平均有8个独立的回声。

    pingTrig = new OutputPort(trig, false);
    pingEcho = new InterruptPort(echo, true, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeBoth);  // it is not really an echo
    pingEcho.OnInterrupt += (p, s, t) =>
    {
        if (s == 0)
            pingFall = t.Ticks;
        else
            pingRise = t.Ticks;
    };

然后

    pingEcho.EnableInterrupt();
    pingTrig.Write(true);
    Thread.Sleep(1);
    pingTrig.Write(false);
    Thread.Sleep(35);      // I hate waiting
    pingEcho.DisableInterrupt();

和

    int Distance { get { return (int)((pingFall > pingRise) ? (pingFall - pingRise) : maxPingDistance); } }

的某个地方。

在netduino上，硬件会获得中断，但会排队稍后收到的事件。幸运的是它是Timestamped。

从另一个中断例程中做很多事情也是非常糟糕的。设置一个标志，指示应该处理按钮按下，并退出中断。然后在常规主循环中，执行ping工作（脉冲触发，等待回声）。从技术上讲，你并不是真正处于中断程序中，但我认为从一个好的实践中可以看出它更有意义。对待它就好像你一样。

答案 2 :(得分：1)

可能有点晚了，但我在SIG上看不到1K电阻，它出现在第一个链路上。由于电流强度，这可能会导致问题。

答案 3 :(得分：0)

我肯定建议使用带有Ping传感器的上拉电阻器，这些超声波传感器几乎都是相同的设备 - 从20世纪70年代开始使用宝丽来SX-70陆地相机来确定距离。

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