Button help

[flotulopex]

I can't make it work with the BUTTON command.

So I tried the other way and use the simple IF..THEN command.

But again, I have the same unexpected result. The Led starts to blink when I press the button. As I release the button, it never "toggles" as I want it to do.

Since this program behavior is the same in both cases (BUTTON and IF..THEN commands), I assume something is wrong with some register settings.

I was thinking about a bouncing problem, but I'm not sure about that.

Here is my code; where do I miss something?

'PIC 16F88
'Button is on PORTB.3 (Pin 9) Pressed = 0V
'Led is on PORTB.4 (Pin 10)

OSCCON = %01100000 'Internal RC set to 4MHZ
TRISB = %00001000 'RB3 is an Input, all others are Outputs
'----------------------------------------------------------------

' IF..THEN
MAIN:
IF PORTB.3 = 0 then SWITCH_LED
goto main

SWITCH_LED:
pause 100 'Debounce
toggle PORTB.4
goto main

end

'----------------------------------------------------------------
' BUTTON

'BVar var byte
'BVar = 0
'
'MAIN:
' BUTTON 9, 0, 255, 255, BVar, 0, SWITCH_LED
' goto main
'
'SWITCH_LED:
' pause 100 'Debounce
' toggle PORTB.4
' goto main

END

[Melanie]

MAIN:
IF PORTB.3 = 0 then SWITCH_LED
goto main

SWITCH_LED:
pause 100 'Debounce
toggle PORTB.4
goto main

So what happens above when you keep your finger pressed on the button for longer than 100mS? Your LED will keep toggling every 100mS...

Try this...

MAIN:
IF PORTB.3 = 0 then SWITCH_LED
goto main

SWITCH_LED:
pause 100 'Debounce
toggle PORTB.4
While PortB.3=0:Wend ' Wait here for Button to be released
goto main

[homebrewer]

' Try CMCON=7 as mister_e has stated in reply#3
' now you can query input pins
' from this point it's up to you, how your led should work

CMCON=7

MAIN:
IF PORTB.3 = 0 then SWITCH_LED
goto main

SWITCH_LED:
pause 100 'Debounce
toggle PORTB.4
goto main

end


' Regards
' Johann

[Melanie]

CMCON has no effect on PortB on this PIC.

[homebrewer]

Hello Melanie,
you are very right. I have looked into the datasheet after my reply.
I was too overhasty - sorry!

[Melanie]

Appologies are unnescessary.

flotulopex reported that his LED blinks when he pushes the button, that's because there's only a 100mS Pause in the loop and you toggle the LED-ON, and with your finger still on the button, 100mS later you toggle it OFF, and with your finger still on the button, the LED toggles again 100mS later... etc etc until the end of time.

You need to ensure that once the LED toggles, it doesn't do so again until the Button is pressed anew. There are MANY, MANY ways of doing this. The example I posted simply waits for the user to remove his finger from the button before proceeding further.

[flotulopex]

Thank you Melanie,

Actually, it still doesn't work.

Each time I press the button, the Led lights up and as soon as I release the button, the Led switches off. At least, it doesn't blink anymore while the button is pressed.

It just doesn't want to toggle!

To make sure my button is correctly connected, is this schematic okay?
> Vdd-R10k-PORTB.3 and the button (normally open) is derived from PORTB.3 to Vss.

Since I can't make it work with this simple program, my last guess would be that my PIC is defect. I tried with other ports but there is no change. I shall receive another PIC tomorrow.

By the way, is there any utility tool to check the PIC's health?