At 10:57 AM 6/21/2004 -0500, you wrote:
>At 09:16 AM 6/21/2004 -0400, Byron A Jeff wrote:
>
> >On Mon, Jun 21, 2004 at 01:03:35AM -0500, rad0 wrote:
> >> When making a pcb, should you tie the unused pins directly to
> >> ground,
> >
> >Absolutely not! Ouch! If for whatever reason the software ever sets that
> pin to a high output, then you've just blown your output buffer.
>
>While this borders on a religious flamewar, I've never seen a micro that
>wasn't capable of withstanding a short to VCC or GND on an output pin.

I agree with this! Someone, hire this man!

>That being said, I would generally agree, set them as outputs, and leave
>them untied, or add a series resistor to ground, and make them output low.

Yes, it can cause other problems if the power supply is weak- perhaps
adding nasty states where the unit doesn't start up properly or half-dies.

>Input with a pullup would be second choice.

Yup.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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