OH, btw, let us know what you do try and the results. It will help others to incorporate them into their designs. I'm not sure if I still have it but it was a old book on grounding and shielding techniques to reduce EMI. I'm sure there is something similar and probably less detailed on the internet about proper grounding techniques as well as filtering and protection. Michael ----- Original Message ---- > From: trossin > To: piclist@mit.edu > Sent: Thursday, March 27, 2008 1:55:43 PM > Subject: [PIC] very slight ESD events wake up my sleeping PICs > > > I've built a few "executive" (I'm just a grunt geek) toys and two of them > have the same problem. That is when I get up from my chair, they turn on. > Both of these toys have push buttons to activate them. When the button is > pushed they do their thing then go to sleep. I enable wake up on port B > change and use the internal pull up resistor. On my latest toy I added a 1K > pull up to try to stop this problem from happening (it reduces the problem > but does not eliminate it). One toy uses the 16LF628A and the other uses a > 16LF873A. One runs on two AA cells while the other runs on 3 AA cells. > > On the toy with the 1K pull up (the 16LF873A), I put the PIC in a metal case > but did not ground the case. The case is just "floating". On this device I > once had an arc to the case and it required me to pop out the battery to > reboot it. I think that grounding the case should solve the problem but I'm > not sure. > > The toy with the 16LF628A is just an exposed PC board but has a 5 inch > twisted pair wire for the switch. > > Has anyone else had problems like this? It only is a problem for me with > projects that use the wake from sleep on interrupt feature. Any ideas on > how to fix it. I guess I could use at 220 Ohm resistor but the lower I go > the more power that is wasted when the button is pushed. > -- ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist