c# - 无法使用 .net micro fw 轮询超声波传感器的脉冲宽度

Question

我正在关注将 C# 和 .net 微框架与视差 Ping 传感器连接的众多示例之一。

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

教程一
https://www.ghielectronics.com/community/codeshare/entry/123

教程二
http://forums.netduino.com/index.php?/topic/1721-parallax-ping-ultrasonic-sensor/

我的传感器已正确连接到我的 netduino plus 的 5v 输出、接地和 gpio 0。(我尝试了不同的端口，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低脉冲。它卡在每个教程中的第二个 while(true) 循环中。此外，我的视差 LED 似乎一直亮着，根据文档，它应该随着每次 ping 脉冲而闪烁，而不是无限期地亮着。我乱用了 MS.SPOT.CPU.GPIO0 和 SecretLabs Pins.GPIOD0 枚举。 secret 实验室引脚产生一个永远不会退出第一个 while(true) 循环的闪烁 LED，而 MS.SPOT 端口产生一个永远不会退出第二个 while(true) 循环的 LED 灯。这是我在 MF 编程的第一天。谁能帮我指出可能是什么问题？

操作视频 https://dl.dropboxusercontent.com/u/62170850/20140606_153029.mp4

看起来我已连接到引脚 10 和 13，但实际上没有。角度有误导性。我实际上插入了 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 : 读:错误
06/01/2011 00:00:34:17:模式:输出
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:信号脉冲开始
06/01/2011 00:00:34:17:模式:输出
06/01/2011 00:00:34 : 17 : 读:真
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 : 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 : 读:错误
06/01/2011 00:00:34:WAITING线路状态变为真。
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:34:17:模式:输入
06/01/2011 00:00:34 : 17 : 读:错误
06/01/2011 00:00:35 : 17 : 模式:输入

Answer 1

我在我的 NetDuino Plus 上实现了你的代码，经过一些修改(我没有和你做的完全一样的传感器，所以我不得不稍微修改你的代码)它似乎工作得很好。所以在对代码进行一些回溯之后，我注意到你正在使用

Cpu.Pin.GPIO_Pin0

按照我的老习惯写成

Pins.GPIO_PIN_D0

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

所以改变

Cpu.Pin.GPIO_Pin0

到

Pins.GPIO_PIN_D0

这应该可以解决您问题中所述的问题。