Yup, according to the schematic the USB chip is powered from the host. Look on the top left of page 3. I believe the line labeled P_DVCC powers the rest of the thing when the USB is attached. On the top right of page 3 is a section labeled MOTE POWER that shows P_DVCC going through D22 to some version of VCC. IF you can find and destroy that D22 diode you'll probably achieve power independence...
Or you could send messages via the radio instead of being hardwired, but the radio transmission would use a chunk of (milli-)amps and might throw off your measurements. MS Eric Decker wrote: > I beleive the tmote sky is a telosb repackaged. you can find the telosb > schematics on http://www.tinyos.net/scoop/special/hardware/ > > Take a look and I suspect what is happening is that the USB interface > chip is > powered by USB power so you'll have to figure out some other way of > powering that chip if you disconnect USB power. > > Probably the simpler approach is to figure out the USB power is used to > power the mote and disconnect that on the board. > > eric > > > On Fri, Jan 9, 2009 at 11:34 AM, Jimmy <[email protected] > <mailto:[email protected]>> wrote: > > Hi, > > I am looking for some help regarding the TMote Sky motes. > > My problem: I want to simulate the draining battery using external > circuitry (i.e. using a programmable power supply), but to do that the > USB power must be cut-off and still need to communicate with the host > computer. So, I disconnected the 5V power line from the USB cable, and > when I do that the host computer cannot be able to see the Tmote > connected to its USB and hence not able to program it. > > I also tried to program the TMote Sky when it is getting power from > 2-AA batteries and USB power cut-off, and the result is that the host > computer cannot see the TMote Sky. > > Is there a way to program the TMote Sky with USB connected and without > using USB power (5V). > > Please help me on this regard. Sentilla has discontinued support for > the Tmote Sky (http://www.sentilla.com/moteiv-transition.html). > > Thank you, > Jimmy > _______________________________________________ > Tinyos-help mailing list > [email protected] > <mailto:[email protected]> > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > > > > > -- > Eric B. Decker > Senior (over 50 :-) Researcher > Autonomous Systems Lab > Jack Baskin School of Engineering > UCSC > > > ------------------------------------------------------------------------ > > _______________________________________________ > Tinyos-help mailing list > [email protected] > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help -- Platform: WinXP/Cygwin TinyOS version: 1.x, Boomerang Programmer: MIB510 Device(s): Mica2, MicaZ, Tmote Sensor board: homebrew _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
