Newbie - 16F628A and switch latching

[malc-c]

Hee hee - fancy seeing you here

Yes I have downloaded the manual, and had it open last night whilst I was developing the program, and as manuals go its really good to get newbies like myself up and running.

Must admit, that I'm having more fun (and luck) with PBP than I did with JAL. PBP seems more logical in its commands and the structure of using them.

Alain, let me into a secret, is that Melanie in her avitar... brains as well as beauty - wow !!

[Acetronics2]

Hee hee - fancy seeing you here

Alain, let me into a secret, is that Melanie in her avitar... brains as well as beauty - wow !!

In fact, Mel is some like Charly in the "Charly's girls" TV series ... I do not think anyone on this forum knows her real appearance ...

We only know she says she likes to wear leather clothes at night, and is a bit bored about charming guys hoping to get something from her brain ...

May be she'd love to find a bunch of red roses and some Champagne at her door rather than the New up to date Compiler ....

Talk to her gently, and she'll give you the best from her ...

That's part of what I understood here ... not to break the magic.

Alain

[Melanie]

There are those that have sent boxes of red roses...

...and there are those that have sent boxes of chocolates...

...boxes of diamonds are a little slower in coming - but I'm working on it...

...and there are those that have seen a little more of me than others (I seldom refuse an invite to dinner - especially if you're buying - but can you afford a genuine up-town girl?) *smiles*

...and Yes, that's really me in the avatar... if you're real nice I just might change it for a while to something more sophisticated - but I'm always worried that I'll distract you from your work (or play)...

[mister_e]

... if you're real nice I just might change it for a while to something more sophisticated -

I have a feeling of what it could be Maybe i'm in the 3rd category ... LOL easy to start some rumor here

BTW Melanie, if you change your Avatar to 'something more sophisticated', i feel that some end-of-class student here could be shocked OR spam your PM! May i bet on the second one

[Melanie]

My PM is already spammed...

Dear Miss Whiplash... Thank you for last nights session... I won't be able to sit down for a week, but it was worth every minute... PS My PIC still doesn't work.

Now, now Steve... people might get the wrong idea on how you ended up in hospital...

[malc-c]

I'm hoping that you guys and Miss whippy, sorry Mel can tell me why the following code won't work correctly.

Having managed to sort out the delay for the debounce I had each LED bing turned on, latched and turned off by activation of the corresponding reed switch - Great !

However I now want to evolve the code so that the following happens. The siding has the buffer at the left, and trains enter from the right. A reed switch (sw1) is placed at the start of the siding (on the right), a train enters the siding and activated sw1 and LED1 is lit. The train continues to the end of the siding where it activates the second reed switch (sw2) and thus LED2 is lit, and the operator shuts off the power. So far so good.

Now the operator can re-arrange the train and place the loco at the other end ready to go back on the main layout. When it does sw1 is then activated again, but this time I need it to clear both LED1 and LED2. Ok I thought, lets simply have a new varible (swset5) that is toggled only when swset1 and swset2 are high.. but it won't work. activating sw1, then sw2, then sw1 again just turns off LED1, LED2 remains lit

Here is my code (I've yet to try the BUTTON command, but maybe that will happen when I come to tidy up the code ??)

@INTRC_OSC_NOCLKOUT
@WDT_ON
@PWRT_ON
@MCLR_OFF
@BOD_ON
@LVP_OFF
@CPD_OFF
@PROTECT_OFF

CMCON=7
TRISB=%00000011         'set RB0 & 1 as input and the rest output

SW1 var PORTB.0          'switch input pin 6 (RB0)
SW2 var PORTB.1          'switch input pin 7 (RB1)


LED1 var  PORTB.4       'LED1 on pin 10 (RB4)
LED2 var  PORTB.5       'LED1 on pin 11 (RB5)

Swset1 var bit
Swset2 var bit

Swset5 var bit

low led1
low led2 
                
Swset1=0 
Swset2=0

swset5=0                'Var swset is set low

Main:
if SW1=0 then            'If switch is LOW (Grounded) then
Toggle Swset1            'change swset1 from 0 to 1
pause 500                'debounce delay
endif

if SW2=0 then            'If switch is LOW (Grounded) then
Toggle Swset2            'change swset2 from 0 to 1
pause 500                'debounce delay
endif

If Swset1=1 then         'if swset1 is 1
high led1                'then turn on RB4 (and hence the LED)
else
low led1                 'else, LED is off
endif

If Swset2=1 then         'if swset2 is 1
high led2                'then turn on RB5 (and hence the LED)
else
low led2                 'else, LED is off
endif

If swset1=1 and swset2=1 then
toggle swset5
endif
if swset5=1 and sw1=0 then
low led1
low led2
else 
high led1
high led2
endif

End

I have even tried removing the "else" part at the end of the code so it reads

If swset1=1 and swset2=1 then
toggle swset5
endif
if swset5=1 and sw1=0 then
low led1
low led2
endif

But that still fails to work correctly.

Any advice guys and gals ??

[Acetronics2]

Hi, Malc

as SWset5 is tested AFTER the swset1 ... your condition never can happend, or during so little time, it can't work properly.

Alain

[mister_e]

... I won't be able to sit down for a week, but it was worth every minute...

Now, now Steve... people might get the wrong idea on how you ended up in hospital...

How dare you post our private stuff in public

LOL! yeah maybe you're right... but damn you should be really strong to break my arms, legs and spinal cord. Guys, be aware of that!

LOL Melanie, at least i wish it could be true

Ok let's stop it here.. there's somebody who need help here, but Alain give some great tips.

[Acetronics2]

Ok let's stop it here ...

Thanks to Luciano, ve've a good idea of uptown girls at night ...

cool, Malc ... cool !!!

Alain

[Melanie]

There is another way of thinking here Alain...

Once a switch has closed (as detected by the first IF/THEN) then the assumption is that whatever event caused it to close (or open) is not a False Alarm and the event intended to happen (eg a User pressing a button). You therefore need no futher IF/THEN's to see if the contacts are still closed after the debounce time period expries.

All you have to do is delay looking at that switch again for a period of time greater than any possible contact bounce to ensure you don't register that event a second time (as would happen if you used interrupts for example).

Now the delay time is really down to the application. I tend to use 100mS for Keyboard Buttons, because that gives an 'auto-repeat' of 10cps which is quite nice when viewed on a display. Naturally, if you're timing something that happens a lot quicker, then you need to reduce the bounce delay time, but if you get it too short, you'll run into the multiple contact closure problem.

It's difficult to guage and is done mainly by look/see and a bit of experience because different switches (be they contacts on a Switch, Relay or a Reed) all exhibit different closure properties and have different bounce periods. Best method I've found is to overkill the delay as much as possible.

The best method for registering an event, but discarding any False Alarms, is to see how long a switch remains closed over a period of time. That then will require multiple IF/THEN's both at the beginning and at the end of the debounce period.