Weirdest thing ever

Started by April 3, 2004
I set up an extremely simple program to alternately blink 2 LED's. I
have my output pins on my 16F628 connected to 470 Ohm resistors then
to the LED. They don't alternate, but when I touch one of the
resistors, then everything works fine. Any ideas??




need more info. please, like are you sourcing current from the pic
through the resistor into the LED to ground? Else, if you are sinking
it, it might stay hot even though you turn the output off.

Also, what's with "everything working right when you touch" . . . are
you using a crystal or the intosc? What do the LED's do when the don't
work "right" . . . on all the time? off all the time? --- wrote:
> I set up an extremely simple program to alternately blink 2 LED's. I
>
> have my output pins on my 16F628 connected to 470 Ohm resistors then
> to the LED. They don't alternate, but when I touch one of the
> resistors, then everything works fine. Any ideas?? >
>


__________________________________




Well, it goes from PIC through resistor to LED to ground. When i am
touching it, and applying a little pressure, it works fine. One LED
stays on for half a second, then shuts off as the other turns on, etc.

When it is not working right, just the first LED stays on. It does
not go off and the other LED does not go on.

This one has me stumped..
--- In , jrem <jrem123@y...> wrote:
> need more info. please, like are you sourcing current from the pic
> through the resistor into the LED to ground? Else, if you are
sinking
> it, it might stay hot even though you turn the output off.
>
> Also, what's with "everything working right when you touch" . . .
are
> you using a crystal or the intosc? What do the LED's do when the
don't
> work "right" . . . on all the time? off all the time? > --- honamos@y... wrote:
> > I set up an extremely simple program to alternately blink 2
LED's. I
> >
> > have my output pins on my 16F628 connected to 470 Ohm resistors
then
> > to the LED. They don't alternate, but when I touch one of the
> > resistors, then everything works fine. Any ideas??
> >
> >
> >
> > __________________________________
>




is it soldered up or in a breadboard? I've had some breadboards that
are iffy . . . the connections get goofed from putting to big of wire
in them . . . --- wrote:
> Well, it goes from PIC through resistor to LED to ground. When i am
> touching it, and applying a little pressure, it works fine. One LED
> stays on for half a second, then shuts off as the other turns on,
> etc.
>
> When it is not working right, just the first LED stays on. It does
> not go off and the other LED does not go on.
>
> This one has me stumped.. >
> --- In , jrem <jrem123@y...> wrote:
> > need more info. please, like are you sourcing current from the pic
> > through the resistor into the LED to ground? Else, if you are
> sinking
> > it, it might stay hot even though you turn the output off.
> >
> > Also, what's with "everything working right when you touch" . . .
> are
> > you using a crystal or the intosc? What do the LED's do when the
> don't
> > work "right" . . . on all the time? off all the time?
> >
> >
> > --- honamos@y... wrote:
> > > I set up an extremely simple program to alternately blink 2
> LED's. I
> > >
> > > have my output pins on my 16F628 connected to 470 Ohm resistors
> then
> > > to the LED. They don't alternate, but when I touch one of the
> > > resistors, then everything works fine. Any ideas??
> > >
> > >
> > >
> > >
> >
> >
> > __________________________________
> >
>


__________________________________




Breadboard.... is it possible that my breadboard is a POS? Any good
way to test? --- In , jrem <jrem123@y...> wrote:
> is it soldered up or in a breadboard? I've had some breadboards
that
> are iffy . . . the connections get goofed from putting to big of
wire
> in them . . . > --- honamos@y... wrote:
> > Well, it goes from PIC through resistor to LED to ground. When i
am
> > touching it, and applying a little pressure, it works fine. One
LED
> > stays on for half a second, then shuts off as the other turns on,
> > etc.
> >
> > When it is not working right, just the first LED stays on. It
does
> > not go off and the other LED does not go on.
> >
> > This one has me stumped..
> >
> >
> >
> > --- In , jrem <jrem123@y...> wrote:
> > > need more info. please, like are you sourcing current from the
pic
> > > through the resistor into the LED to ground? Else, if you are
> > sinking
> > > it, it might stay hot even though you turn the output off.
> > >
> > > Also, what's with "everything working right when you
touch" . . .
> > are
> > > you using a crystal or the intosc? What do the LED's do when
the
> > don't
> > > work "right" . . . on all the time? off all the time?
> > >
> > >
> > > --- honamos@y... wrote:
> > > > I set up an extremely simple program to alternately blink 2
> > LED's. I
> > > >
> > > > have my output pins on my 16F628 connected to 470 Ohm
resistors
> > then
> > > > to the LED. They don't alternate, but when I touch one of
the
> > > > resistors, then everything works fine. Any ideas??
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> > > __________________________________
> > >
> > __________________________________
>




VOM or DMM from point to point, make sure you have continuity. Or just
try different holes. Breadboard contacts get worn from putting to big
of gauge wire in the grips . . .
--- wrote:
> Breadboard.... is it possible that my breadboard is a POS? Any good
> way to test? > --- In , jrem <jrem123@y...> wrote:
> > is it soldered up or in a breadboard? I've had some breadboards
> that
> > are iffy . . . the connections get goofed from putting to big of
> wire
> > in them . . .
> >
> >
> > --- honamos@y... wrote:
> > > Well, it goes from PIC through resistor to LED to ground. When i
>
> am
> > > touching it, and applying a little pressure, it works fine. One
> LED
> > > stays on for half a second, then shuts off as the other turns on,
> > > etc.
> > >
> > > When it is not working right, just the first LED stays on. It
> does
> > > not go off and the other LED does not go on.
> > >
> > > This one has me stumped..
> > >
> > >
> > >
> > > --- In , jrem <jrem123@y...> wrote:
> > > > need more info. please, like are you sourcing current from the
> pic
> > > > through the resistor into the LED to ground? Else, if you are
> > > sinking
> > > > it, it might stay hot even though you turn the output off.
> > > >
> > > > Also, what's with "everything working right when you
> touch" . . .
> > > are
> > > > you using a crystal or the intosc? What do the LED's do when
> the
> > > don't
> > > > work "right" . . . on all the time? off all the time?
> > > >
> > > >
> > > > --- honamos@y... wrote:
> > > > > I set up an extremely simple program to alternately blink 2
> > > LED's. I
> > > > >
> > > > > have my output pins on my 16F628 connected to 470 Ohm
> resistors
> > > then
> > > > > to the LED. They don't alternate, but when I touch one of
> the
> > > > > resistors, then everything works fine. Any ideas??
> > > > >
> > > > >
> > > > >
> > > > >
> > > >
> > > >
> > > > __________________________________
> > > >
> > >
> >
> >
> > __________________________________
> >
>


__________________________________




At 11:17 PM 4/3/2004 +0000, wrote:

>I set up an extremely simple program to alternately blink 2 LED's. I
>have my output pins on my 16F628 connected to 470 Ohm resistors then
>to the LED. They don't alternate, but when I touch one of the
>resistors, then everything works fine. Any ideas??

Sounds like a hardware problem.
Is this a white plugboard? They have a tendency to not make contact, especially if you don't clean the "gunk" off when you pull resistors out of a tape strip.




Low voltage programming is enabled by default - you need to pull RB4
down to ground through a resistor - say 220 ohms.

MCLR' needs to be pulled high through a 10k resistor.

I have had the same issue and these fixes seemed to help!

--- In , David VanHorn <dvanhorn@c...> wrote:
> At 11:17 PM 4/3/2004 +0000, honamos@y... wrote:
>
> >I set up an extremely simple program to alternately blink 2
LED's. I
> >have my output pins on my 16F628 connected to 470 Ohm resistors
then
> >to the LED. They don't alternate, but when I touch one of the
> >resistors, then everything works fine. Any ideas??
>
> Sounds like a hardware problem.
> Is this a white plugboard? They have a tendency to not make
contact, especially if you don't clean the "gunk" off when you pull
resistors out of a tape strip.


oh, and another thing, make sure you're not poking any leads through
the bottom of the breadboard's insulation into a conductor that is
hot . . .

breadboards are great for prototyping, but they can be debug hell,
specially for high freq analog.

--- In , jrem <jrem123@y...> wrote:
> VOM or DMM from point to point, make sure you have continuity. Or
just
> try different holes. Breadboard contacts get worn from putting to
big
> of gauge wire in the grips . . . >
> --- honamos@y... wrote:
> > Breadboard.... is it possible that my breadboard is a POS? Any
good
> > way to test?
> >
> >
> > --- In , jrem <jrem123@y...> wrote:
> > > is it soldered up or in a breadboard? I've had some
breadboards
> > that
> > > are iffy . . . the connections get goofed from putting to big
of
> > wire
> > > in them . . .
> > >
> > >
> > > --- honamos@y... wrote:
> > > > Well, it goes from PIC through resistor to LED to ground.
When i
> >
> > am
> > > > touching it, and applying a little pressure, it works fine.
One
> > LED
> > > > stays on for half a second, then shuts off as the other turns
on,
> > > > etc.
> > > >
> > > > When it is not working right, just the first LED stays on.
It
> > does
> > > > not go off and the other LED does not go on.
> > > >
> > > > This one has me stumped..
> > > >
> > > >
> > > >
> > > > --- In , jrem <jrem123@y...> wrote:
> > > > > need more info. please, like are you sourcing current from
the
> > pic
> > > > > through the resistor into the LED to ground? Else, if you
are
> > > > sinking
> > > > > it, it might stay hot even though you turn the output off.
> > > > >
> > > > > Also, what's with "everything working right when you
> > touch" . . .
> > > > are
> > > > > you using a crystal or the intosc? What do the LED's do
when
> > the
> > > > don't
> > > > > work "right" . . . on all the time? off all the time?
> > > > >
> > > > >
> > > > > --- honamos@y... wrote:
> > > > > > I set up an extremely simple program to alternately blink
2
> > > > LED's. I
> > > > > >
> > > > > > have my output pins on my 16F628 connected to 470 Ohm
> > resistors
> > > > then
> > > > > > to the LED. They don't alternate, but when I touch one
of
> > the
> > > > > > resistors, then everything works fine. Any ideas??
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > > > __________________________________
> > > > >
> > > >
> > >
> > >
> > > __________________________________
> > >
> > __________________________________
>




I pulled RB4 down like you said, and I already had MCLR high. I
really can't tell if the leads are poking down too far, but in my
experience with breadboards, I've never had it push through
insulation. Interesting observation...
When I touch the resistor that is connected to the first LED, it
increases in intensity, then the circuit functions normally....
--- In , "jrem123" <jrem123@y...> wrote:
> oh, and another thing, make sure you're not poking any leads
through
> the bottom of the breadboard's insulation into a conductor that is
> hot . . .
>
> breadboards are great for prototyping, but they can be debug hell,
> specially for high freq analog.
>
> --- In , jrem <jrem123@y...> wrote:
> > VOM or DMM from point to point, make sure you have continuity.
Or
> just
> > try different holes. Breadboard contacts get worn from putting
to
> big
> > of gauge wire in the grips . . .
> >
> >
> >
> > --- honamos@y... wrote:
> > > Breadboard.... is it possible that my breadboard is a POS? Any
> good
> > > way to test?
> > >
> > >
> > > --- In , jrem <jrem123@y...> wrote:
> > > > is it soldered up or in a breadboard? I've had some
> breadboards
> > > that
> > > > are iffy . . . the connections get goofed from putting to
big
> of
> > > wire
> > > > in them . . .
> > > >
> > > >
> > > > --- honamos@y... wrote:
> > > > > Well, it goes from PIC through resistor to LED to ground.
> When i
> > >
> > > am
> > > > > touching it, and applying a little pressure, it works
fine.
> One
> > > LED
> > > > > stays on for half a second, then shuts off as the other
turns
> on,
> > > > > etc.
> > > > >
> > > > > When it is not working right, just the first LED stays on.
> It
> > > does
> > > > > not go off and the other LED does not go on.
> > > > >
> > > > > This one has me stumped..
> > > > >
> > > > >
> > > > >
> > > > > --- In , jrem <jrem123@y...> wrote:
> > > > > > need more info. please, like are you sourcing current
from
> the
> > > pic
> > > > > > through the resistor into the LED to ground? Else, if
you
> are
> > > > > sinking
> > > > > > it, it might stay hot even though you turn the output off.
> > > > > >
> > > > > > Also, what's with "everything working right when you
> > > touch" . . .
> > > > > are
> > > > > > you using a crystal or the intosc? What do the LED's do
> when
> > > the
> > > > > don't
> > > > > > work "right" . . . on all the time? off all the time?
> > > > > >
> > > > > >
> > > > > > --- honamos@y... wrote:
> > > > > > > I set up an extremely simple program to alternately
blink
> 2
> > > > > LED's. I
> > > > > > >
> > > > > > > have my output pins on my 16F628 connected to 470 Ohm
> > > resistors
> > > > > then
> > > > > > > to the LED. They don't alternate, but when I touch one
> of
> > > the
> > > > > > > resistors, then everything works fine. Any ideas??
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > > >
> > > > > > __________________________________
> > > > > >
> > > > >
> > > >
> > > >
> > > > __________________________________
> > > >
> > >
> >
> >
> > __________________________________
> >