Mike, On the subject of schematics, perhaps you'll find this page informative:
http://www.tinyos.net/scoop/special/hardware/#telos Cheers, Rob On 1/26/06, Michael Schippling <[EMAIL PROTECTED]> wrote: > It sounds like there is something else already connected to the ADC input. > The bare input impedance should be in the K's of ohms so your 10K ladder > should be reasonably accurate. > > Is this one of those devices that has an onboard sensor that gets switched > on internally somehow? Have a look at all the code you are using and see > if it's expecting some other signal...or try some other ADC inputs. > > I don't know nuthin about the telos, including where to find the schematic > and actual working code, so that's about all I can say. > MS > > > Roger Fuerst wrote: > > Hello, > > > > I am doing a project with two other people at Portland State University > > using telosb and tmote Sky motes. We are trying to take a temperature > > reading using a thermistor using an ADC channel on the external sensor > > ports. To test an analog input we hooked up a voltage divider from Vcc > > to ground (on the 10 pin expansion slot pins 1 and 9 respectively) using > > 10k resistors. We had 6 separate measuring points: 3V, 2.4V, 1.8V, > > 1.2V, 0.6V and ground as measured with a voltmeter. When we hooked up > > the ADC port input at Vcc we got a reading FFF hex with we took to > > mean 100%. At the 2.4V node we got 17 hex which is almost a zero > > reading. The remaining readings went down from there. We then tried > > reducing the resistor values, and when the overall resistor series value > > is about 200 ohms, we got reasonable conversion results. We were > > surprised at the sensitivity to resistance. Does this make any sense? > > Any insight would be greatly appreciated. > > > > TIA, > > > > Roger Fuerst > > > > > > ------------------------------------------------------------------------ > > > > _______________________________________________ > > Tinyos-help mailing list > > [email protected] > > https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > _______________________________________________ > Tinyos-help mailing list > [email protected] > https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > _______________________________________________ Tinyos-help mailing list [email protected] https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
