Flip Flop

[tazntex]

The little light bulb went off in my head this morning about using a flip flop to turn on or off a pin on portb.1. Ok, I thought I could push a momentary button one time on portb.0 and portb.1 would go high, pushing the button once more and releasing it, portb.1 would go low. Hmmm, sounds easy, so off to my keyboard:

flipflop VAR BYTE
flipflop=%00000000

loop:
IF portb.0 = 1 && flipflop.0 = 0 THEN
flipflop.0=1
portb.1=1
ENDIF

PAUSE 100

IF portb.0 = 1 && flipflop.0 = 0 THEN
flipflop.0=1
portb.1 = 0
ENDIF

IF portb.0 = 0 THEN 'With this the button would have to be release so it would
flipflop = flipflop ^ %00000001 'not continue to toggle
ENDIF

goto loop


Would this be the way to do this?

Thanks for your suggestions.
END

[peterdeco1]

There has to be an easier way. I'm assuming portb.0 is held high with a pullup. Try something like this:

START:
IF PORTB.0 = 0 THEN TOGGLE PORTB.1 : GOTO WAITFORRELEASE
GOTO START

WAITFORRELEASE:
PAUSE 50
IF PORTB.0 = 0 THEN WAITFORRELEASE
GOTO START

[mister_e]

Not sure to understand the whole thing... but if you just want to Toggle the state of a pin with a single button... i would suggest


IF PORTB.0 = 0
TOGGLE PORTB.1 ' or PORTB.1=PORTB.1 ^1
WHILE PORTB.0=0 : WEND ' wait 'till button is released
PAUSE 50 ' debounce delay
ENDIF

Still doable in a ISR...

[Melanie]

I'd put the debounce BEFORE the nested While:Wend as so...
[code]
IF PORTB.0 = 0
TOGGLE PORTB.1 ' or PORTB.1=PORTB.1 ^1
PAUSE 50 ' debounce delay
WHILE PORTB.0=0 : WEND ' wait 'till button is released
ENDIF
code

[Melanie]

I'd put the debounce BEFORE the nested While:Wend as so...


IF PORTB.0 = 0
TOGGLE PORTB.1 ' or PORTB.1=PORTB.1 ^1
PAUSE 50 ' debounce delay
WHILE PORTB.0=0 : WEND ' wait 'till button is released
ENDIF

Otherwise you're not debouncing the original Button-Press and risk running straight through the button-release code.

[mister_e]

;) yeah but noise on switches/push-buttons appear on both rising and falling edges???

But yeah, here it could be safer to debounce before, as the TOGGLE will execute pretty fast, and the code next to the IF might be long enough to act as Rising edge debouncing.. who know ;)

I'm not a fan of reading push button directly in many cases... Timer interrupt do the whole thing in background and also do the debouncing... why doing simple when you can do it 'complicated' :D