Grounding the user may be acceptable if the user is in an environment where they expect to be grounded randomly. Some associates of mine had made some airline counter equipment associated with luggage scales and under certain conditions people putting luggage onto the scales were inputting vv high esd levels into the equipment. Normal esd protection helped but did not totally eliminate the problem. Finally they provided a "wiping contact" which caused the high voltage party to be grounded if they came withing touching distance of the appropriate equipment. The grounding resistance in such cases can be quite high - 1 megohm or more. You will find that commercial wrist-straps have a 1 megohm resistor (possibly more) in their grounding lead to avoid (or at least reduce the probability of) electrocution of the user should they choose to touch a live contact. -----Original Message----- From: Peter Lorand Peres Date: Tuesday, 16 December 1997 05:07 Subject: Re: esd protection >It is VERY bad to ground the person, it involves risk of electric shock >from anything not connected through a fault current breaker, including the >project's power supply. As far as I know, the only place where you can >ground the operator safely is in a production environment where the units >are not powered.... ... snip >On Mon, 15 Dec 1997, Justin Crooks wrote: > >> Well, how about grounding the person touching the pins? If this isn't >> feasable, you could use an RC filter... >> >> Subject: esd protection >> Date: Thursday, December 11, 1997 3:13 PM >> hello, >> I have one question for all you guys/girls >> In a project with a PIC16C84 the inputs can be touched bij fingers, >> my question : how can i protect the i/o against ESD charges ? >> >> Kind regards, >> >> Rob Aerts