Hi, Thanks. A vibratab is a sensor that can sense vibration. You can find it on MEAS-SPEC.COM. I use ADC12 Channel_0 and the ground pin to connect the sensor. As you suggested, I ground the input and get a stable zero reading. So may be it is due to the problem that the power the vibratab generates is too low to drive the ADC12 so that the data is just floating, right?
Thank you for your help! Best wishes, Chenni Quoting Michael Schippling <[EMAIL PROTECTED]>: > Ok I give...the first page of google results for "vibratab" are > links to Canadian pharmacies...what is it you're connecting to? > > Second, try grounding the input you are sampling. You should get > a stable value of some kind. It may be that the software you are > using sets a mid-value zero-point, but I would more expect to > see a zero reading. Make sure you are using the ADC input that > you think you are sampling. You can also connect a pot between > Vcc and ground and drive the input to see if you get 0-max. > (I think it's 12 bits so that would be 4096 if my math still holds). > > Then we'll try connecting your sensor. By the name "vibra" one gets > the idea that it may be an AC output, which means you'll have to > deal with nyquist sample rates. > > MS > > > Chenni Qian wrote: >> Hi, >> >> I am using the TinyOS and Tmote Sky to collect data from a >> vibratab. I installed the nesC code to the Tmote Sky. But the data >> collected is very strange. When the vibratab is not vibrating, if >> I set the sample period as 256ms, the amplitude of the PC >> oscilloscope is below 100 while if the sample period is 20ms, the >> data becomes around 1200. Besides, even if I remove the vibratab >> so that there is nothing input to the ADC12, the amplitude shown >> is still about 800. Is it the software or the hardware that cause >> the problem? The vibratab is in well performance and the code is >> the original code. How can I solve the problem? >> >> Thank you very much! >> >> Best wishes, >> >> Chenni >> _______________________________________________ >> 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
