Hi Wolfgang, On Wed, May 25, 2011 at 3:28 PM, Wolfgang Denk <w...@denx.de> wrote: > Dear "J. William Campbell", > > In message <4ddc6f46.4090...@comcast.net> you wrote: >> >> Well, it is not quite that simple. The "accuracy" of the 1 ms >> interrupt rate is controlled in all cases I know about by the resolution >> of the programmable divider used to produce it. It appears that the x86 > > I mentioned a couple of times before that accuracy has never been a > design criterion. Please also keep in mind that there are areas in > the code where we block interrupts, and we make zero efforts to detect > or compensate for this in the timer code. This simply is not > important. We are not talking about ppm here, we are talking about > somting that is just good enough for what it is being used, and that > allows easily for +/- 10% tolerances.
With the prescaler design we are discussing, as long as we have access to a free-running tick counter, it does not matter one iota if the interrupt is delayed by one tick, a hundred ticks or a thousand ticks privided it eventually happens within the roll-over interval of the tick counter And if get_timer() is called in the meantime, the roll-over interval gets reset Regards, Graeme _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
