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
