B4R Question How to implement a Do-while for a Pushbutton?

[Mark Read]

A simple question but I cannot find an answer in the forum. Using the Arduino Mega and a simple pushbutton or switch.

I need to add a pushbutton to my project and code it like this:

While Pushbutton is being pressed

'Do this
turn on motor and move accordingly

end

Releasing the button would then stop the motor. I think I have to be carefull not to block the main thread.

The point of this is to move a horizontal arm slowly downwards to set the position of a mechanical end switch, clients request.

How can I code this? Suggestions please.

Thank you.

 

[Cableguy]

In the pushbutton event (true) Set a timer to true and to false when the push button is released.
Then in the timer tick do the needed ops. Timers do not block the main thread in b4r

 

[Mark Read]

Great, thank you Cableguy. Simple question, simple answer.

Stealing a bit of code from Erel and tested on an Arduino Uno with a piece of wire.

Sub Process_Globals
    Public Serial1 As Serial
    Private btn As Pin
    Private timer1 As Timer
    Private i As UInt=0
End Sub

Private Sub AppStart
    Serial1.Initialize(115200)
    Log("AppStart")
    btn.Initialize(btn.A0, btn.MODE_INPUT_PULLUP) 'Using the internal pull up resistor to prevent the pin from floating.
    btn.AddListener("Btn_StateChanged")
    timer1.Initialize("timer1_Tick",1000)
    Log("Waiting....")
End Sub

Sub Btn_StateChanged (State As Boolean)
    'Log("State: ", State)
    'state will be False when the button is clicked because of the PULLUP mode.
    If State=False Then
        timer1.Enabled=True
        Log("Button pressed")
    Else
        timer1.Enabled=False
        Log("Button released")
        i=0
    End If
End Sub

Sub timer1_Tick
    'turn on motor till button is release or whatever
    i=i+1
    Log("i= ",i)
End Sub

 

[tigrot]

I was thinking about this post. Why not simply use btn_StateChanged to switch motor on and off? On state=on activate relay , on Off deactivate. It's an event and this doesn't block thread.

 

[Mark Read]

The button controls a stepper motor not a relay. I need the timer to switch the coils but theoreticall you are right.

 

[Cableguy]

One issue that came to mind is button de-bouncing! Doing it directly on the button event may give origin to erroneous behaviour. By setting a timer (the first tick will only happen after the interval set) this de-bouncing is automatically done... unless of course you do it the hard (ware) way.

 

[Mark Read]

I will find out next week when my hardware comes and I can try the code.

 

[tigrot]

For this a 100ms delay is more than enough. But how can a micro GPIO line control a stepper motor directly?

 

[Cableguy]

Usually it doesn't. It controls a stepper driver.

 

[Mark Read]

The motor is controlled via a L293 chip, not directly of course. Normally the motor is controlled with a timer which has varied times, ie. the speed will be controlled in mm/s. The purpose of the switch is to override the automatic setting and operate the motor at a slow speed continuously while the button is being pressed. This is required by the client in order to setup vaious end switches before automatic operation.