The periodic recalibration of the DCO got removed because it didn't take into account the cpu going to sleep which messed up the calculation. I've got some ideas of how to fix this but haven't had time to actually implement them yet.
Also with the new msp430 chips that use 16x overclocking and higher base DCO clocks it is less of an issue. Things have to drift quite a bit before the uart starts to mess up. If you do use the 32KiHz clock for buad, the max you can go is 9600. The max you can run the UART at is 1/3 of BRCLK which can be selected from ACLK, SMCLK, etc. eric On Sat, Jan 2, 2010 at 10:13 PM, Thomas Schmid <[email protected]>wrote: > Hi Steve, > > There is a function that executes the recalibration of the DCO in the > Msp430ClockP.nc file. You could do it yourself whenever you need it. I > think the periodic recalibration got removed because most applications > don't use the DCO for time critical things. > > An other solution for you would be to switch the UART clock over to > the 32kHz crystal (ACLK clock), depending on the speed you need. 9600 > baud is absolutely no problem to get using that clock. > > Cheers, > > Thomas > > On Sat, Jan 2, 2010 at 3:25 PM, Steve Gulick > <[email protected]> wrote: > > Hi > > > > IN the past it seemed the periodic recalibration of the DCO in the MSP430 > > had been removed for some reason. Has that been reinstated? Or is there > some > > means to programaticaly force a recalibration? > > > > I had been using the DCO as the UART clock source. I found that even at > 9600 > > baud - in *outdoor* applications the typical temperature changes would > cause > > the async comm to stop working. I confirmed that the problem was > frequency > > drift by using a scope and resetting the MSP430 - thus recalibrating the > > DCO - would always fix it. > > > > If there is some reason an automatic, periodic recalibration can not be > > done, in my present application the MSP430 always initiates the > > communication and it is infrequent so it if there was a routine to force > a > > recalibration that would work for me - otherwise I will need to use an > > external accurate clock source for baud rate generation. > > > > Thanks > > Steve > > _______________________________________________ > > Tinyos-help mailing list > > [email protected] > > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > > > > _______________________________________________ > Tinyos-help mailing list > [email protected] > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > -- Eric B. Decker Senior (over 50 :-) Researcher
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