Yes, it will work fine. I have not tested it with a 16F84A but on the
16F84 and 16C71 I have projects running continuously that have ~10 volts
on RA4 no problem for two years now.

On one of them I thought it had hurt the chip but it turned out to be
something else stupid I'd done, not related to RA4.

Cheers,

Bob Blick

On Wed, 24 Oct 2001, Allen Mahurin wrote:

> I'm using a 16F84, so you guessed it ... I'm talking
> about RA4.  It's the only unused pin I have for a
> project, and I'm wanting to clock a decade counter
> 4017 with it.  I know it can't source much, so I want
> it to sink current (trigger the counter on a negative
> going pulse).  Anyway, the question is:
>
> The PIC runs on 5V, while the 4017 runs on 9V.  If I
> tie the clock input of the 4017 to 9V through a 4.7k
> or 10k resistor, and use the PIN input to pull it low
> (tied between the resistor and 4017 input), will this
> hurt the PIC?  I know it would be sinking current, and
> it would be low, which is OK.  But will putting 9V
> into the open-collector output cause problems?  I'd
> like to see if anyone knows from experience before I
> kill a good chip.  :)   If this won't work, does
> anyone have any other low-parts count alternatives?

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads