1 switch, 1 pin, "single click, double click..."

[Acetronics2]

Hi, Steve

Might work with two " Button" commands following each other, as debounce time is effective ONLY if condition TRUE ...

he,he ...

Alain

[mister_e]

Maybe... but as you know, I never use Button, so...

Someone could also go crazy and use CLKI + timer interrupt.... this allow 1,2,3,4,5... click triggers for a x period of time, with a real minimum of code line, something <10 code line I guess.

[Gusse]

Hi, Steve

Might work with two " Button" commands following each other, as debounce time is effective ONLY if condition TRUE ...

he,he ...

Alain

I haven't use Button -command too, but couple of IF - THEN with PAUSE works for me.

IF But = 0 then         'Button is pressed and debounce detections starts 
    PAUSE 100           'wait 100ms or some other more suitable time
    IF But = 0 then     'if button is still held down then do something
                        'start timer or loop for 2nd button press detection ...

I think, some time window must be defined otherwise you will be waiting that other press forever...

Also nice to hear that Steve had similar thoughts

BR,
-Gusse-

[erice1984]

thanks for all the input guys.

I played around with the count for a little while, thought it was working pretty consistently. I re-evaluated where the button was going to be positioned and thought the double clicking could become annoying.

The if-then statements turned out to be very nice change, and 10 fold more consistent.

[peterdeco1]

I did this a while ago. I just removed the "bells and whistles" and should work the way it is. It works like a single or double click on a mouse.

START:
IF PORTA.1 = 1 Then START 'BUTTON NOT PUSHED STAY HERE
GoSub MOUSECLICK 'CHECK FOR DOUBLE CLICK
if click = 1 then let click = 0 : goto something
if click = 2 then let click = 0 : goto somethingelse
goto start

MOUSECLICK:
IF PORTA.1 = 0 Then MOUSECLICK 'stay here until switch is released
LET CLICK = CLICK + 1 'switch released
IF CLICK >=2 Then Return 'LIMIT CLICKS TO 2
pause 500 'switch has to be pushed 2 times within 1/2 second for double click
IF PORTA.1 = 0 Then MOUSECLICK 'switch pushed again
Return

[Gusse]

I did this a while ago. I just removed the "bells and whistles" and should work the way it is. It works like a single or double click on a mouse.

START:
IF PORTA.1 = 1 Then START 'BUTTON NOT PUSHED STAY HERE
GoSub MOUSECLICK 'CHECK FOR DOUBLE CLICK
if click = 1 then let click = 0 : goto something
if click = 2 then let click = 0 : goto somethingelse
goto start

MOUSECLICK:
IF PORTA.1 = 0 Then MOUSECLICK 'stay here until switch is released
LET CLICK = CLICK + 1 'switch released
IF CLICK >=2 Then Return 'LIMIT CLICKS TO 2
pause 500 'switch has to be pushed 2 times within 1/2 second for double click
IF PORTA.1 = 0 Then MOUSECLICK 'switch pushed again
Return

As you can see from picture, debounce can make port to change state between 0 - 1 for several times. This would make code above to generate two clicks if pressed longer than 500ms (even button is pressed once). More reliable way is to check that button is still held down after some time (debounce delay) and after that go forward.

Source of picture and some more info about debounce
(I hope it is OK to link this picture to this forum? If not then Admin can remove it.)

Problem is here

MOUSECLICK:
IF PORTA.1 = 0 Then MOUSECLICK 'stay here until switch is released

Click (similar to picture above): If shorter than 500ms then OK, but longer pulses than 500ms will generate 2 clicks. You have no debounce filtering in this loop.
Of cource, some can say that this is very unlikely scenario. Maybe, but it can happen if you don't have anykind of filter (i.e RC-loop) at input.

BR,
Gusse

[peterdeco1]

You are right Gusse. When I removed all the "bells and whistles" , I removed the debouncing and also a timer where "pause 500" is. If you double click before the 500 mS is up, it immediately makes click = 2 and returns.

[turbokinetic]

What is challenging is doing this without making the rest of the program be suspended waiting on the second click to happen or not.

The way I have been doing this is to set a bit for each of the following events:

Button pressed
Time expired without second press
Second press happened during time count.

The following sample works. It may look complicated, but it works well. It is part of my car lights controller code which has multiple inputs that have similar logic and all are active at once.

While one input is waiting on a possible second press, the rest of the program is still working and responding to inputs.

I've always found that for best reliability a pushbutton almost always need a small capacitor across the contacts to debounce it. Using the following program, the loop is so short the program can respond very fast. Without a capacitor, the bounce can cause it to give false operation. On a longer program, the remainder of the program loop will be enough delay to debounce the button signal.

The complete lights controller code has over 800 lines of code, and a good portion has to execute every program cycle. Each input is checked once per cycle so there is enough delay to keep bounce from being an issue.

Also, read the state of the input into a temp variable, then use the temp variable to do the logic. This will keep bounce from happening during the logic operations, and causing some really funky stuff to happen! Voice of experience!!

I used the hardware of the lights controller to test this program fragment, so that's why the relays are on it.

Hope this is helpful!
Thanks,
David

'Double-Click example For PIC16F88

'Header for 16F88 CPU I/O modes and Osc. speed...
CMCON=7 'Analog comparators OFF
ANSEL=0 'ADC inputs OFF
'OSCCON=%00000010 ' 31.25 KHz
'OSCCON=%00010010 ' 125 KHz
'OSCCON=%00100010 ' 250 KHz
'OSCCON=%00110010 ' 500 KHz
'OSCCON=%01000010 ' 1 MHz
'OSCCON=%01010010 ' 2 MHz
'OSCCON=%01100010 ' 4 MHz
OSCCON=%01110010 ' 8 MHz

SetupSwitch VAR PORTA.5 'This is a momentary pushbutton
Relay1 VAR PORTB.2      'These outputs close a relay when they are HIGH
Relay2 VAR PORTB.1

SStime VAR WORD         'this counts down to time the second press

x VAR BIT               'buffer variable to keep switch state changes during logic from causing issues.
SSx VAR BIT             'determines change of switch
SS1 VAR BIT             'Set once when SetupSwitch pressed once
SS2 VAR BIT             'Set once when SetupSwitch pressed twice within timefrave

SStime = 0 'These must be initialized to keep from having one false-trigger when circuit sterts up.
SSx = 0

:loop

'------
X = SetupSwitch 
IF X <> SSx Then
 PauseUs 1 'This will help de-bounce switch, but if program is long, you will not need!
 LET SSx = X
   IF X Then
    IF SStime > 0 Then 'If the timer is still counting when a press happens
     SS2 = 1           'set the "double press" variable and
     SStime = 0        'reset the timer
    Else
     SStime = 10000    'When the first press happens, start counting at 10000.
    EndIF
   EndIF
Else
 SS1 = 0
 SS2 = 0  
EndIF

IF SStime = 1 Then 'If no second press has occured, when timer reaches 1, set the "single press" bit.
 SS1 = 1
 SStime = 0
EndIF
'------

IF SStime > 0 Then        'This function to decrement the double-click timer would be done in another
 LET SStime = SStime - 1  'part of the program, probably using a hardware timer. This is just an example. 
EndIF

IF SS1 Then Toggle Relay1 'Each single-click toggles Relay # 1
IF SS2 Then Toggle Relay2 'Each double-click toggles Relay # 2

GoTo loop