Except for very good reaason(s), such as a safety or security-based mandate from a customer, e.g., DOD, FAA, FDA, NRC, etc., why would any designer deliberately make a pin unavailable?

IMHO it is preferable to keep one's options open.  Why burn bridges?

Doug Hewett
Software engineer,
CSDP




-----Original Message-----
From: Herbert Graf [mailto:mailinglist@FARCITE.NET]
Sent: Monday, June 30, 2003 10:59 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [EE]: PCB routing across unused pin?


> >> I was wondering if there is any way to route across an unused
> pin pad on
> >> an SMT PIC?  If I set up the pin as an output, then it is
> >> high-impedence, correct?  So, to the circuit it is not there?
> >
> >        You must set it as an input, not output, and even then
> the voltage on that
> >pin must not go outside the allowed input for a PIC pin. What
> about bending
> >that pin up so it doesn't make contact with the pad? Are you doing SMD or
> >through hole? You could just cut the pin off. TTYL
>
> This would be a VERY bad idea for a 'production' product, as it
> would cause problems when (not if)
> someone forgets to cut/lift the pin.

        I don't see why, the pin will already be set as input, so unless you are
doing something wierd with that trace the "cutting of the pin" is only a
backup.

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