Hi, See page 14 in the datasheet: http://focus.ti.com/general/docs/lit/getliterature.tsp?genericPartNumber=cc2420&fileType=pdf
In the lowest-power transmit mode (-25dBm) the current draw is 8.5mA. Note, however, that prior to sending the message, the default radio stack implementation in TinyOS make the radio enter a random-back-off state, in which the radio is in receive mode. Especially for short messages the power savings possible by reducing the transmission power level are negligible with respect to the power consumed in this random back-off stage. Cheers, Urs ma. pratama wrote: > Quote from you : "The CC2420 draws 18.8mA in receive mode and 17.4mA in send > mode at the highest transmission power level (0dBm)". > > How about the lowest Transmission power (-25dBm)? how much the current draws?? > > --- On Mon, 6/8/09, Urs Hunkeler <u...@gmx.ch> wrote: > > From: Urs Hunkeler <u...@gmx.ch> > Subject: Re: [Tinyos-help] Ask inner resistance of Micaz motes > To: "Michael Schippling" <sc...@santafe.edu> > Cc: "ma. pratama" <spidol_perma...@yahoo.com>, "Tinyos-Help" > <tinyos-help@millennium.berkeley.edu> > Date: Monday, June 8, 2009, 3:42 AM > > Hi, > > As MS already said, the "resistance" of the mote will vary based on the tasks > being executed on the mote. If you need to estimate the current drawn by a > mote and the remaining power in the batteries, then probably the best > approach is to use a fuel gauge like the DS2770 as suggested in an earlier > discussion (see below). I think, the DS2770 is not in production anymore, but > you can find similar products: > http://para.maxim-ic.com/en/search.mvp?fam=batt_stat&295=Fuel%26nbsp%3BGauge&tree=powersupplies > > You might also want to read this application note: > http://www.maxim-ic.com/appnotes.cfm/appnote_number/121 > > The above recommendations are taken from an interesting discussion quite a > while ago that I remembered. The two relevant posts are: > http://mail.millennium.berkeley.edu/pipermail/tinyos-help/2007-January/022092.html > http://mail.millennium.berkeley.edu/pipermail/tinyos-help/2007-January/022099.html > > As for the help-list wisdom about the receive-mode drawing more current than > the send mode: From the CC2420 datasheet, the CC2420 draws 18.8mA in receive > mode and 17.4mA in send mode at the highest transmission power level (0dBm). > I can confirm this with measurements that I made myself. The reason for this > is probably (meaning, I have no citations) that sending is a pretty > straight-forward process and the output power is limited by the laws for > using the license-free radio bands (1mW in the 2.4GHz band). The receive > mode, however, uses a much more complicated circuit to amplify and decode the > received signal. Because of the low transmit power permitted by law, the > radio module manufacturers try to extend the communication range by > implementing sophisticated filters to eliminate background noise and the like. > > When calculating the power consumption of communications consider that before > sending a single message the radio enters a random back-off state during > which the radio is in receive mode and typically draws more energy than > during the actual transmission mode. > > Cheers, > Urs > > Michael Schippling wrote: >> Well, you see...in a word. No. >> At least I don't know of any. >> >> But more to the point, it's a meaningless question >> because the current draw, and thus "inner resistance", >> varies with the functions being performed. E.g., if the >> radio is transmitting, more current is being drawn (and, >> according to help-list wisdom, receiving uses even more >> power....which makes no sense to me, but not much does >> anymore either). >> >> If you have current measurements for the various states >> you can calculate the effective resistances and then >> guess how long the mote is in each state to arrive at >> a total power use. >> >> MS >> >> ma. pratama wrote: >>> yes..thats exactly what i do right now..using a small resistor and measure >>> the battery each hour..but if i could know the inner resistance it should >>> be much easier to measure the current..are there any repositories that >>> revealed the micaz resistance?? >>> >>> --- On *Sat, 6/6/09, Michael Schippling /<sc...@santafe.edu>/* wrote: >>> >>> >>> From: Michael Schippling <sc...@santafe..edu> >>> Subject: Re: [Tinyos-help] Ask inner resistance of Micaz motes >>> To: "ma. pratama" <spidol_perma...@yahoo.com> >>> Cc: tinyos-help@millennium.berkeley.edu >>> Date: Saturday, June 6, 2009, 9:33 AM >>> >>> That's a bit of a problem as the current draw changes with operation. >>> Folks have used a small resistor in series with the battery to measure >>> the current. Search this list for more info. >>> >>> MS >>> >>> ma. pratama wrote: >>> > Hi all,,, >>> > >>> > I want to measure the current after usage in the micaz motes. I >>> will using moteview to monitor the voltage in the micaz motes, so i >>> only need the inner resistance inside the micaz motes to determine >>> the current by simple formula : V = I . R. >>> > >>> > Do anyone know how much the inner resistance of the micaz motes?? >>> thanks.. > > > > _______________________________________________ Tinyos-help mailing list Tinyos-help@millennium.berkeley.edu https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
