Yes this is right and common to every microcontrollers sold in the world, so it is not a problem to solve but simply to deal with it. You have no chance to change this functionality simply because it isn't possible. If you need some sort of timing related to seconds or fractions of seconds you may use a microcontroller with internal real time clock or use an external real time clock. You may find rtc with 10 milliseconds resolution. Massimo Manca, Micron Engineering Jens Hildebrandt wrote: >Right, but when you have to use the same clock for your timer you have to deal >with odd counter intervalls (e.g. 67.8ns with 14,7456MHz). So you have to decide >what you want - error free UART or clean counter intervalls. > >Micron Engineering wrote: > > > >>This problem is common to every microcontroller, it is not new; if baud >>rate error is important you have to choose the correct crystaland this >>is not difficult since there are a lot of frequencies available. Of >>course the microcontroller clock will be lower then possible maximum. >> >>acetoel wrote: >> >> >> >> >>>Thanks >>>I noticed that today when looking at the Baud Rate error. With 20Mhz >>>is near 0.12% and with 14.xx is near 0.02%. It's quite a difference >>>and 1 Mhz in the processor clock will not make a significant >>>difference... >>>Thanks >>>Ezequiel >>> >>>--- In lpc2000@yahoogroups.com, "Leon Heller" <leon_heller@h...> >>>wrote: >>> >>> >>> >>> >>> >>>>----- Original Message ----- >>>>From: "acetoel" <acetoel@y...> >>>>To: <lpc2000@yahoogroups.com> >>>>Sent: Tuesday, September 28, 2004 12:03 PM >>>>Subject: [lpc2000] LPC performance and Clock frecuency >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>>>Hello... >>>>>I have seen boards with 10MHz, 14.xxxMhz and 20Mhz. All with the >>>>> >>>>> >>>>> >>>>> >>>PLL >>> >>> >>> >>> >>> >>>>>set so the chip runs at 60Mhz more or less... >>>>>But really, is there any difference if I use a 20Mhz crystal >>>>>oscilator than a 10Mhz? >>>>>IF there is no difference between crytal speed.Why so many >>>>> >>>>> >>>>> >>>>> >>>people >>> >>> >>> >>> >>> >>>>>use the 14.xxxMhz crystal osc? >>>>> >>>>> >>>>> >>>>> >>>>It gives accurate baud rates for the UARTs. >>>> >>>>Leon >>>> >>>> >>>> >>>> >>> >>> >>> >>>Yahoo! Groups Links >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >> >>[Non-text portions of this message have been removed] >> >> >> >> >> >>Yahoo! Groups Links >> >> >> >> >> >> >> >> > > > > [Non-text portions of this message have been removed]
Message
Re: [lpc2000] Re: LPC performance and Clock frecuency
2004-09-28 by Micron Engineering