Hi David, 1. This is right, but should not have too much of an impact on the actual power consumption or the results. I am considering an active circuit to compensate this. Also, a smaller resistor (e.g. 1 Ohm) would reduce this effect, but you'd need a better instrument to measure the resulting lower voltage values.
2. Currently, I do not use anything special as what I see already corresponds pretty much to what I expected (at least the form of the curve, not necessarily the measured values). LEDs are in my opinion not good for keeping track of the state of the application as they consume a considerable amount of energy themselves. You could use digital I/Os and record the evolution with additional channels on the oscilloscope. 3. I happen to have a Tektronix DPO4000 series oscilloscope (not sure about the exact model) in the lab where I work, so I use this. It even has an Ethernet interface with which I can control the measurements from a computer. I cannot recommend any particular oscilloscope as I simply have not enough experience. If you evaluate different oscilloscopes, pay attention to the inherent acquisition noise (when I short circuit the input terminals on my scope I still see noise with an amplitude of up to 10mV). The noise can usually be reduced by reducing the bandwidth of the acquisition. The bandwidth is another thing you want to look at. Depending on what you want to measure, this should be from a couple of 10s of kHz to a couple of MHz. Typically, a scope will acquire a wave form, which you then need to save before you can acquire the next wave form (or you can overwrite the old one without saving it). The scope should have enough memory to acquire a waveform over a meaningful time window with enough temporal resolution. Cheers, Urs David Li wrote: > Hi Urs, > > Thanks for the clarification. I think now I understand your setup. Only a > few more questions: > > 1. Using your example, then the voltage on the mote itself is the remaining > from 3v - 0.2v = 2.8v. Is this right? > > 2. How would you correlate the measurements on the Oscope to the events on > the mote? Did you have to instrument any code? > > 3. I am curious about the model of the Oscope in your test. I know Janos > used HP34401A. Is there any model you would recommend for this task? > > Thanks. > > David _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
