Now, is it possible that the accelerometer is "warming up". Previously you said that you were _sure_ the the value was stable when the first measurement was made. Can you try it with a truly fixed voltage on the A0,1 input? The fact that the InternalVoltage is OK would indicate that initial S/H time might not be the culprit...
MS Dimas Abreu Dutra wrote: > Hello Everyone, > > Sorry for taking so long to answer. But here are my comments: > > * I noticed the error on the first readings when using the external > channels (A0 and A1). It happens on both tmote invent that I have access > to. I am using the tmote's own sensors (accelerometer), and I've done no > hardware modifications. > > * When I used the Msp430InternalVoltageC the first reading was OK. > > * I believe on Michael's hypothesis, which is that the sampling time of > the sample and hold is not correctly set on the first run. The ADC > counts I get are like if there was not enough time to charge the > capacitor, they are proportional to the input voltage, but much smaller. > > ~Dimas~ > > > On Thu, Jun 19, 2008 at 8:45 AM, Jan Hauer <[EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED]>> wrote: > > What ADC channel are you using, external (A0-A7) or internal (>7)? > does the conversion require stable reference voltage (if so, is your > application wiring to AdcReadClientC or Msp430Adc12ClientAutoRVGC()?). > Do you see the same result when you use > tinyos-2.x/tos/chips/msp430/sensors/Msp430InternalVoltageC? > > Jan > > _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
