Are you using the TinyOS distribution provided by Moteiv with our Tmote Sky modules? If not, you may have an outdated version of the source code.
If you follow the instructions in our document "Connecting External Sensors", it will configure the ADC pin to input automatically. If you miss a step, the ADC pin will remain output and sink current from any device hooked up to it. I believe the problem here is that you're using someone else's outdated TinyOS distribution. I would recommend updating to CVS (do not use TinyOS 1.1.14, it has some significant bugs) -Joe On 12/7/05, Sandro Fornili <[EMAIL PROTECTED]> wrote: > > > > Since I am a newcomer in this field, I anticipate my apologies if the > question is too silly! > > > > By modifying tinyos-1.x/apps/Oscilloscope as suggested at > http://www.moteiv.com/community/Connecting_External_Sensors > , I tried to convert a 2.9 V analog signal applied to pin 3 of the 10-pin > connector (i.e., the ADC port A0) of a TelosB. I got a reading of ca. 550 > instead of something around 4000. Then I measured the input current when the > 3-V AVCC voltage (pin 1 of the connector) is applied to pin 3 through a > tester. I got a reading of about 30 mA, which is much larger than what I > expected. > > > > I obtained the same results considering the pin 5 (i.e., the ADC port A1) of > the connector. > > > > Moreover, a tmote sky device gave the same results. > > > > Am I doing something wrong? What can I do to make A/D converter working with > higher input impedance? > > > > Thank you in advance for your attention. > > > > Sandro > > > > Sandro L. Fornili > > Dipartimento di Tecnologie dell'Informazione > > Università degli Studi di Milano > > Via Bramante 65, 26013 Crema (CR), Italy > > > > Tel. +39-02-503-30067 > > Fax +39-02-503-30010 > > > _______________________________________________ > 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
