debouncing switches with a timer interrupt?

[Bruce]

Mike,

I would suggest delegating switch debounce/management to the ISR

With his switch inputs on RB7-RB4, how would you go about that without waiting for a switch release, and then clearing the int-on-change flag bit?

Wouldn't releasing the switch re-trigger the interrupt?

[Mike, K8LH]

Mike,

With his switch inputs on RB7-RB4, how would you go about that without waiting for a switch release, and then clearing the int-on-change flag bit?

Wouldn't releasing the switch re-trigger the interrupt?

Oh no, I wouldn't use IOC interrupts in this application Bruce. Bouncing would be problematic. I would use periodic timer interrupts and poll the switches as in the example in post #15. And since OP is going to include RTC or Stopwatch functionality, periodic timer interrupts make sense.

[Bruce]

Oh! I see what you meant now. Good idea.

Newer types like the 16F193x series IOC are a lot easier to use. These don't require reading the port to clear IOC flag bits, and they can be set to trigger on any edge..

[DDDvvv]

thanks guys, all this ideas work! now, all i have to do is implement the rtc and beeper, which are ready to be merged with this code.

once again, thanks.

ps; not that im complaining, but is there any other menu builder app in picbasic?

[dagger]

yo he implementado esto y funciona correctamente

[DDDvvv]

hi, again, im trying this piece of code, from a previous post

RB_SUBMenuLoop:
' BTN_PLUS is the Next Choice button
   IF BTN_PLUS=1 THEN
      BTN_PLUS=0
      ...
   ENDIF
' BTN_PREV is the Exit button
   IF BTN_PREV=1 THEN
      BTN_PREV=0
      RETURN
   ENDIF
' BTN_NEXT is the Goto SubMenu Choice button
   IF BTN_NEXT=1 THEN
      BTN_NEXT=0
      ...
   ENDIF
GoTo RB_SUBMenuLoop

then i have this code scanning port b, through a 1ms interrupt:

Changed = PortB ^ OldPort
         IF Changed.4 = 1 THEN     ; Pick your pin
         OldPort = PortB
         BTN_PLUS = 1
         ENDIF

this code is incrementing one at a time, which is what i want, but the only problem is that it is incrementing on a rising and falling edge of a button push. so if i push the btn_plus, bmenupos increments by 1, and if i release it, bmenupos increments again.

i want it to increment only on the rising edge, not on the falling edge. any ideas?

[Mike, K8LH]

When you exclusive-or "new" and "old" a resulting 1 bit indicates a change of state (either a new hi or new press, or a new lo or new release). You need to filter these "change" bits. If you AND the "change" bit with the "old" bit you filter out the "new press" bits and you're left with "new release" bits. If you AND the "change" bit with the "new" bit you filter out the "new release" bits and you're left with the "new press" bits.

Hope this helps.

Cheerful regards, Mike

'
'  swnew  ____-----_____-----_____   new switch sample (positive logic)
'  swold  _____-----_____-----____   switch state latch
'  delta  ____-____-____-____-____   changes, press or release
'  newhi  ____-_________-_________   new press bits
'  newlo  _________-_________-____   new release bits
'
    swnew = PortB                  ' sample active hi switches
    delta = swnew ^ swold          ' changes, press or release
    newhi = delta & swnew          ' get "new press" bits
    newlo = delta & swold          ' get "new release" bits
    swold = swnew                  ' update switch state latch
    IF newhi.4 = 1 THEN            ' 
      BTN_PLUS = 1                 '
    ENDIF