Urs Hunkeler ha scritto: > I have not tried this yet, I am just thinking about it. > > Here is a link with a summary of different Oscilloscope replacements: > http://opencircuits.com/Oscilloscope > > There is an open-source application called "xscope" for Linux: > http://xoscope.sourceforge.net/ > > Apparently, sound cards have an input range on the line-in from -1V to > 1V. Most sound cards should support a sampling rate of >40kHz and a > sampling depth of 16 bits. The biggest unknown (to me) is whether the > sound cards filter out the DC component (e.g. you cannot measure > voltage, but only changes in voltage). If this is the case, I would need > to find a different solution. Otherwise we can probably expect something > like this: The sound card might have an antialiasing filter with a > cut-off frequency of 20kHz, so we should get a temporal resolution of > around (1s / 20'000 =) 50us (I think even 100us is good enough for me). > We might have to amplify/attenuate the signal from the mote. If we make > a simple input circuit to measure current in the range of 0-50mA (a > typical MicaZ or Iris mote with the radio, CPU and all LEDs on and also > writing to the Flash should not draw more current) and in order to keep > the circuit simple map this to 0-1V (we loose half of the input range), > we should get a resolution <2uV. Considering noise and imperfections in > the circuit the accuracy is probably more around 10uV, but even 100uV > are probably good enough for me.
Wow. :) Your idea is amazing! Thank you very much for the project description. If you realize it, keep me informed because I am very concerned. Greetings and good luck, -- Francesco Ficarola <francesco.ficarola_at_gmail_dot_com> Presidente LUG-PV (http://lugpv.netsons.org) Mailing List: lugpv_at_lists.linux_dot_it [GPG KeyID: 0xDBA99D92] http://lugpv.netsons.org/gpgkeys/francesco_ficarola.asc Il nuovo modo di fare ricerca: www.tradoogle.it
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