Dear John Griessen. Thanks for your reply
The sensor cable have three wires in the next configuration. - Analog out. - Ground (bare) - Excitation I'm connecting directly the excitation wire to the GIO(I/O)'s TelosB. Is not OK this configuration? Then the soil sensor needs an external power source? I've read that the mote output pins in TelosB are capable of a maximum of 6 mA at 3.0 V. To each test, is changed wire position in the ADC ports (ADC0, ADC1, ...), maintaining the rest of wires and probe in its before states. The values obtained after the conversion are in m3/m3 putting the probe inside dirt with something of humidity. Below is a sample measuring in the ADC0 port, which is similar than others ports. 0.227704 0.220072 0.238728 0.240848 0.232368 0.24424 0.234064 0.233216 Thanks in advance for your kind answer. Yours sincerely, Alejandro > On 10/16/2012 05:52 PM, [email protected] wrote: >> I'm using a soil sensor which have one wire to excite it, another that >> returns a voltage > > It needs another wire to flow current returning from the voltage source > if it is like soil sensors I use. Is yours a 3 terminal sensor? > > On 10/16/2012 05:52 PM, [email protected] wrote: > > I've connected the wire (Analog output) of the soil sensor to the 6 > ports > > available in the TelosB (in the 6-U28 and 10-U2 pin expansion.) > > ADC0(P6.0), ADC1(P6.1), ADC2(P6.2), ADC3(P6.3), ADC6(P6.6), ADC7(P6.7) > I > > did a test independently, each one per time > > Can't tell what you mean. You might mean you tested some ADC readings > with one sensor 6 different times, or something else. You don't say > if you had the sensor in air, or dry dirt, or damp dirt... Not enough > info. > > > The soil sensors I use need a good ref voltage like the 2.5V output to > give > calibrated results. AVCC will change with battery state depending on > your system -- with telosb -- yes it will drop. > > Sounds like you are piping your Espanol through google translate and > getting some > odd words, like lecture instead of reading WRT ADC readings...so keep it > simple. > > "in this case is that the batterie discharge is very fast > because all time the soil sensor is consuming 2 mA." > > I use a FET switch to isolate and turn off the soil sensors for all but 12 > milliseconds > per reading. It's planned to be open hardware, but I have not published > it well yet. > _______________________________________________ > 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
