具有Raspberry Pi GPIO的保持/按下按钮

Question

I would like my button to do 2 of the following things;

• Do something whenever a button is pushed
• Do something whenever a button is held for a certain amount of time (2seconds)

The current code that I'm working with looks a little like this:

    //Comfirming a letter or sending the word.
    private void btnRightValueChanged(GpioPin sender, GpioPinValueChangedEventArgs e)
    {
        //if button is pressed it will confirm a letter
        if (e.Edge == GpioPinEdge.FallingEdge)
        {
            //code to confirm letter
            ConfirmLetter();

            //if(buttonHeldForAWhile)
            //{
            //Send message
            //SendWord();
            //}
        }
    }

But how can I check whether the button is held for 2 or 3 seconds?

Answer 1

I found a way to fix my problem by using a Stopwatch that measures the time that the button is being pressed.

Above our namespace we need to add this in order for us to use the Stopwatch class.

using System.Diagnostics;

Now we want to declare a Stopwatch by:

Stopwatch stopWatch;

When the button is pressed and held my code will pick that up with the FallingEdge . When it is pressed I also want it to create a new Stopwatch and start it.

When the button is released, which is checked by RisingEdge . I stop the timer and get the time between the 2 events. I then compare the time pressed in an if statement so I can decide what to do with the buttonpress. In this case SendWord, or Append current char and preview it.

    //Comfirming the chosen letter.
    private void btnRightValueChanged(GpioPin sender, GpioPinValueChangedEventArgs e)
    {
        if (e.Edge == GpioPinEdge.FallingEdge)
        {
            stopWatch = new Stopwatch();
            stopWatch.Start();
        }

        if (e.Edge == GpioPinEdge.RisingEdge)
        {
            stopWatch.Stop();
            long duration = stopWatch.ElapsedMilliseconds;

            if (duration > 2000 )
            {
                SendWord();
            }
            else
            {
                //Add the current character to the word
                _currentWordSB.Append(Convert.ToString(_currentChar));

            //    //Reset currentChar aswell
                _currentChar = ' ';

            //    //The user confirmed the morse sequence and wants to start a new one, so we reset it.
                _morseCode.Clear();

            //    //Preview the word
                PreviewLetter();
            }
        }
    }

If there is any better way to tackle my problem, please let me know but so far this solution works for me.

I needed this as I was working on a Raspberry Pi project with Morse code input via buttons. That input then had to be displayed on a LCD screen. If the user was satisfied with his input he could then send it to the other user(s) by holding the Right button for 2 seconds.