A little aside....you CAN measure the REAL battery voltage on the micas because they have a fixed voltage connected to the battery measurement ADC input (at least the mica2 does, I'm forgetting if the Z is the same now...). It's counter- intuitive, but when you convert the fixed ref it's apparent value _rises_ as the battery (which is used as the ADCref) droops. Tricky engineers...
But I stand by my opinion that you don't have to adjust for battery voltage when converting any ratio-metric input that uses the same battery for its power. MS Agnelo Silva wrote: > Hi, > > I just want to get an accurate set of RSSI from a collection of received > messages. > What I understood, up to this moment, is that RSSI from the TOS message > (received packet) is a) only a raw value (we need to convert it to a > useful value, like dBm), and b) is DEPENDENT on the battery level of the > mote which received the packet. > > So, if the battery level of the mote is not considered (or "fixed" in > 3V) in our samples, it means that our set of measures are not accurate > as desired. > > I would like to confirm if I am right or not in this point. > > []s, > Agnelo Silva > > > On Mon, Jul 14, 2008 at 4:05 PM, wang wei <[EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED]>> wrote: > > hi > Im not sure why do u want the"battery voltage",(Do you wanna see > differnet RSSI value under different voltage?) actually, you cant > measure the value of battery, but you can control the transmit power > > good luck > Vi > > On Mon, Jul 14, 2008 at 11:56 AM, Agnelo Silva <[EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED]>> wrote: > > I am preparing the code to make the conversion of the "raw" RSSI > value available in received message (indirectly a reading from > ADC INPUT 0 - RSSI MONITOR). Although, I am developing using T1 > (TinyOS 1.x), I read the T2 doc > http://docs.tinyos.net/index.php/Rssi_Demo and noted the same > thing I observed in some examples I saw in the Internet: what > are about the battery reading for each message? > > I understood that, according to the manufacturer manual, VRSSI = > 'raw counts' * battery voltage / 1024. So, for me, the correct > code must present a reading of the battery before sending any > 'raw RSSI' for conversion. > > Also, sometimes, I saw in some codes/messages, a direct use of > '3' in the place of "battery voltage". Reading the schematic of > the Mica2, I didn't see any voltage regulator to make such > assumption and I am not sure about this approach considering the > CC1000 data sheet. > > So, what I have in mind is to develop the algorithm to send > informations to a certain procedure (internal function for > locally conversion or external program): > 1) First reading: send (battery level, raw RSSI) > 2) Next reading: if the battery level doesn't change according > to a certain threshold, send (raw RSSI) > 3) Next reading: if the battery level does change according to > a certain threshold, send (new battery level, raw RSSI) > > Please, I would like to hear if I misunderstood the topic "at > all" or, if not, I would like to hear different solutions or > suggestions. > > []s, > Agnelo R. Silva > > > > _______________________________________________ > Tinyos-help mailing list > [email protected] > <mailto:[email protected]> > > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > > > > > ------------------------------------------------------------------------ > > _______________________________________________ > Tinyos-help mailing list > [email protected] > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
