I don't know what sort of signal the sensor puts out or at what level. If it's a piezo device it may be a very low level AC that needs amplification, like a microphone. Study of the sensor's data sheet (which, it seems, none of use out here in cyberspace can find) is indicated.
MS Eric Keller wrote: > I searched on the measurement specialties site and got no hits for vibratab. > Is it a piezo device? I have been using the MSI piezo wire hooked to a > telosb, > and have some strange results because I'm not using signal conditioning, > and the piezo material acts like a capacitor, so the voltage floats. > It works for my application, but it is sample rate dependent. > Eric > > > > > On Fri, Aug 8, 2008 at 9:50 PM, Chenni Qian <[EMAIL PROTECTED]> wrote: >> 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 >> > _______________________________________________ > 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
