> > > From: Thanai Anantawatanawitaya > > Hi all, > > > > Does anyone know how long a PIC could works a certain code such as a real > > time clock which is never be interrupted or reset until it stops or hangs > > by itself? > > > > Let's assume that there is no bug in code at all and power supply is in a > > very good condition. Also watchdog is disabled. You may think this is a > > strange question but I think it's interesting because I'm developing a > > product that has to be powered all the time until user throw it away > > because he buys a new model, not because the old one is dead. > > It will go forever. Well, at least until the chip wears out. Yes, > there is a phenomenon in which the metallisation on the die surface While it may do, it may at any time be hit by a decay product of some radiactive isotope in the packaging, or a cosmic ray, this may cause anything from a change in a register (internal or user) to altering eeprom/eprom/rom The first ones on the list are more probable How often will it happen? I doubt microchip charecterises chips for this, the only way would be to impact the chip with cosmic ray like events, and see what average interehaction rate there is. > migrates slowly in the direction of sustained current. Also, the > dopants in the semiconductor junctions will slowly diffuse from thermal > effects. Hard radiation also degrades the die. Atomic bombs going off > in the ionosphere or nearby will probably snuff it. However, except > for The Bomb, for your purposes these processes will not affect the > chip until _way_ past your next product release. If The Bomb goes off > then you will have other things to worry about. > > Regards, > SJH > Canberra, Australia > -- Ian Stirling. | http://www.mauve.demon.co.uk/ AKA Caeser, Bolonewbie. | With information on the PDA I'm making.