David BALDWIN wrote:
>
> Hi,
>
>         As usual, I have some questions today... I am using the check_keys
> routine from Bob Blick. In fact, it only detects falling edges on portA.
> I am searching for a routine that could decide between a single press on
> a switch and a long press on a switch (more than 500ms or 1s). The
> reason is that I don't have so much I/O on my 16C84 and had like one
> switch to have more than one function. Can anybody help?
>

I use a routine in my Timer0 interrupt service that does the following :
        Is button pressed ?
                Yes :   Increase counter BUTTON_COUNTER
                        Is BUTTON_COUNTER > 10 (This value depends on your app)
                                Yes :   Set BUTTON_PRESSED_FLAG
                No :    BUTTON_COUNTER = 0

All you have to do in your main routine, is to look if
BUTTON_PRESSED_FLAG is set.
If you want to use look for long and short presses, do the following :

Use a routine in your Timer0 interrupt service that does the following :
        Is button pressed ?
                Yes :   Increase counter BUTTON_COUNTER
                        Is BUTTON_COUNTER > 20 (This value depends on your app)
                                Yes :   Set LONG_FLAG
                        Is BUTTON_COUNTER > 10 (This value depends on your app)
                                Yes :   Set SHORT_FLAG
                No :    BUTTON_COUNTER = 0
                        Is LONG_FLAG set ?
                                Yes :   Set LONG_BUTTON_PRESSED_FLAG
                        Else is SHORT_FLAG set ?
                                Yes :   Set SHORT_BUTTON_PRESSED_FLAG

All you have to do in your main routine, is to look if
SHORT_BUTTON_PRESSED_FLAG,
or LONG_BUTTON_PRESSED_FLAG is set.

You have to remember to reset the flags after use in your main routine.
If you think
this is a very long and cumbersome method, here are a few points to
consider :
1) Your software never hangs in delay loops
2) The inputs are much better debounced than with just two samples.
3) You work with flags, so you don't have to worry about the debouncing
- it happens
   by itself.
4) If you have multiple inputs, you can optimise the code to be shorter
than other
   methods.
5) If you use this method to debounce keypads, you'll find double
keypresses easy.



--
Friendly Regards

Tjaart van der Walt
mailto:tjaart@wasp.co.za
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