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From: Dombo on 4 May 2008 15:27
Tom�s � h�ilidhe schreef:
>> Just out of curiosity - what are the other pins on the PIC being used
>> for?
>
> I've 12 pins available altogether:
>
> * 7 are going to LED's.
> * 1 is clocking a counter.
> * 3 are taking input from buttons.
> * 1 is turning a piezo speaker on and off.
>
> Here's my current schematic:
>
> http://freepdfhosting.com/uploads/c01e0f0837.pdf
>
> It has NPN transistors where it should have PNP because I've just
> recently changed the chips I'm using. I plan on replacing the bi-polar
> transistors with MOSFET's, just as soon as I figure out which ones are
> suitable. I need one that can pass 500 mA, and another that can pass 2
> A.

You could save two I/O pins if connect the input buttons to a voltage
divider network on one side and the other side of the buttons to an
analog input of your uC.
From: Rocky on 4 May 2008 15:34
On May 4, 8:53 pm, Tomás Ó hÉilidhe <t...(a)lavabit.com> wrote:
> > Just out of curiosity - what are the other pins on the PIC being used
> > for?
>
> I've 12 pins available altogether:
>
> * 7 are going to LED's.
> * 1 is clocking a counter.
> * 3 are taking input from buttons.
> * 1 is turning a piezo speaker on and off.
>
> Here's my current schematic:
>
> http://freepdfhosting.com/uploads/c01e0f0837.pdf
>
> It has NPN transistors where it should have PNP because I've just
> recently changed the chips I'm using. I plan on replacing the bi-polar
> transistors with MOSFET's, just as soon as I figure out which ones are
> suitable. I need one that can pass 500 mA, and another that can pass 2
> A.

Thanks - It explains the pre-occupation with wanting 1 pin to drive
the counter/shiftregister. I think there better ways of handling the
problem, but I'm off to bed now.
Rocky
From: Tomás Ó hÉilidhe on 4 May 2008 16:38
On May 4, 8:27 pm, Dombo <do...(a)disposable.invalid> wrote:

> You could save two I/O pins if connect the input buttons to a voltage
> divider network on one side and the other side of the buttons to an
> analog input of your uC.


Thanks for pointing that out, it hadn't crossed my mind. I'm looking
into it.

Now I just need to find something frivolous to do with two extra
pins :-D Any ideas? I've already got seven segment displays and a
piezo speaker. What else can I put on it? It's a shame they don't have
chips that can give out a smell :P
From: Tomás Ó hÉilidhe on 4 May 2008 21:32
On May 4, 9:38 pm, Tomás Ó hÉilidhe <t...(a)lavabit.com> wrote:
> On May 4, 8:27 pm, Dombo <do...(a)disposable.invalid> wrote:
>
> > You could save two I/O pins if connect the input buttons to a voltage
> > divider network on one side and the other side of the buttons to an
> > analog input of your uC.
>
> Thanks for pointing that out, it hadn't crossed my mind. I'm looking
> into it.


Actually do you think it would be worth the hassle having to deal with
the user pressing more than one button simultaneously?
From: Hans-Bernhard Bröker on 6 May 2008 16:39
s0lstice wrote:

> Put half an amp through your LEDs without current limiting resistors
> and you may create one ;->

Actually, I would expect that to produce a sound instead. As in: PING
and they're gone.
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