How to check if a pin is high/low ?

[octal]

Hi,
is there any (internal) SWFBasic command to check if a Pin of a selected port is high or low ?
in PBP we where to use a syntax like

Code: Select all

if PORTD.0 then doSomething

I would like to write a function that check if a Pin passed as a parameter byRef is High or Low, so I have written something like

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Function CheckButton(ByRef aPin As Bit) As Boolean
    If aPin Then 
      Debounce(Temporisation) ...
      If aPin Then   <<<<<<<< SWFBasic do not accept this test
        result = true
        Exit
      End If
    Else
      result = false      
    End If   
End Function

I would like to be able to pass any pin as parameter, for example

Code: Select all

   if CheckButton(PORTD.0) then ....
   if CheckButton(PORTA.3) then ....
   if CheckButton(PORTB.2) then ....

Thanks

[David Barker]

Passing bits by reference is not very efficient, but if you want to do it...

>> If aPin Then <<<<<<<< SWFBasic do not accept this test

Because it is not a boolean expression, try

IF aPin = 1 THEN

or use a typecast. This should also work...

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function CheckButton(byref aPin as bit) as boolean
    result = (aPin = 1)
    if result then
      Debounce(Temporisation) 
      result = (aPin = 1)
    endif
end function 

[octal]

Thank you David,
I can pass the param by value. It's not a problem for me. The ByRef in the code I posted is just a result of Copy/Paste operation from another function I had written (and that affects the state of the Pin).
In this case I'll pass it by value.

regards
Octal

[David Barker]

If you pass by value, you will not be able to read the state of the pin when (or if) the pin changes state after the debounce, because you are only passing a copy of the pin state - so you will have to pass by reference.

I was just pointing out it is not very efficient, as the compiler has to use indirect addressing on a byte and then create a mask to access the bit value.

[octal]

If you pass by value, you will not be able to read the state of the pin when (or if) the pin changes state after the debounce, because you are only passing a copy of the pin state - so you will have to pass by reference.

...
.

Ahhhhhh .... yes ... you are right David. Thank you very much.

Well,
if I declare my Pins like that

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Dim 
    Button1 as PORTD.Booleans(1),
    Button2 as PORTA.Booleans(2),
    Button3 as PORTB.Booleans(5)

function CheckButton(byref aPin as Boolean) as boolean
    result = aPin
    if result then
      Debounce(Temporisation)
      result = aPin
    endif
end function

And I call it like that 
if CheckButton(Button1) then ....
if CheckButton(Button2) then ....
if CheckButton(Button3) then ....

Does this code do the same? are there any differences from the previous function (in terms of functionnalities) ?

Kind regards

[David Barker]

> Does this code do the same? are there any
> differences from the previous function (in terms of functionnalities) ?

Yes, it looks fine and the functionalty appears to be the same.