Quoting "Van Horn, David" : > > > I am mainly just thinking out loud here. Understanding that some of =20 > you prefer to "short outputs" instead of using weak pull-ups, I =20 > nevertheless am curious as to your design thinking at times when you =20 > actually do want to use a weak pull-up to minimize current yet avoid =20 > serious EMI issues. Or do you just go about selecting weak pull-ups =20 > via "trial & error"? I usually use external resistors for pullups. The internal weak ones are typically a little too weak (and variable) for what I want to see. Resistor networks are cheap and accurate. --sp > > If it's a one-off for your amusement, then do what you like. =20 > Especially if wrong operation has little to no consequence. > > The products I am currently designing are life-or-death. I don't =20 > even have dipswitches. The three switches I do have, have pull =20 > resistors that are activated just before reading, and a series =20 > resistor between the switch and the micro for ESD. A small =20 > capacitor at the micro pin smooths the input, and that ESD resistor =20 > also limits current between the cap and switch, keeping me from ever =20 > exceeding the switch current rating. I mostly use the controlled =20 > pullup scheme because I have to have a very long battery life. =20 > Current wasted into switches during the 999mS when I'm not looking =20 > is just stupid. The impedances are low enough that we pass ESD =20 > without upset, and radiated susceptibility which is normally tested =20 > at 3V/m for this type of product, will still pass test above 150V/m > > How normal people test for ESD Issues: =20 > http://www.teseq.us/products/NSG-435.php > How I test for ESD issues: https://www.youtube.com/watch?v=3D999gLBK77ss > After it passes my test, then it gets formally tested by the first =20 > method. Funny thing, I have never failed formal ESD testing. > > I've always said that embedded systems should "Just Work". Meaning =20 > that you shouldn?t have to even think about it, operation should be =20 > obvious, and it should be dead reliable. > If your new toy from china doesn't work right, you get annoyed or =20 > maybe inconvenienced. > The products I'm designing now, if they don't work, someone dies. > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .