Does anyone know of any reason to not use the 60hz/110VAC signal coming from the electric utility companies to drive an "approximate" elapsed time clock? Isn't that what digital alarm clocks used for their clock source not too many years ago? The board I'm working on doesn't have a crystal that divides down neatly to seconds (milliseconds, etc.) using any of the built in timers/prescalers, and I'm having trouble maintaining a moderately accurate real time clock with it. One of my coworkers stated an opinion that power compaines don't have any guarantee about the accuracy, stability, etc. of the 60hz AC that's associated with our AC power here in the USA, especially when the power grid switches things around, and that if I use that 60hz to drive my clock it'll lose time regularly (i.e., several seconds per day).
Anyone have any comments on this issue?