Hi Peter! Thanks for the clarification. You are completely right: you can get BOTH the LQI and the ED (energy, which is averaged RSSI over 8 symbols), I made a mistake. You cannot get however both the ED and the instantaneous RSSI.
Miklos On Tue, Apr 19, 2011 at 12:56 PM, Peter Trenkamp <[email protected]> wrote: > Hello Umit and Miklos, > > I don't think there is a conversion formula for the LQI between the > values from RF230 chip (Iris mote) and CC2420 (Shimmer mote). > The IEEE 802.15.4 standard defines that this parameter have to use a > range from 0 to 255 but a specific formula to calculate the LQI is not > defined. > The RF230 chip calculates the LQI directly in hardware (values from 0 to > 255) but the CC2420 radio chip only provides an average correlation > value (values from 50 to 110) which can be used to calculate the LQI in > software using RSSI value or through packet error rate measurements but > please refer to the CC2420 datasheet page 49. > > I used the RF230_RSSI_ENERGY flag in my Makefile for the ZigBit Amp > (RF230 radio chip) to get averaged RSSI values over 8 symbol periods > because CC2420 calculates its RSSI value over 8 symbol periods, too. > For me it was possible to get both, LQI and RSSI (averaged over 8 > Symbols with RF230_RSSI_ENERGY flag) values. > > > For the RSSI to dBm calculation I used the information in the > datasheets: > RSSI_dBm = PHY_ED_LEVEL -91 > > For CC2420: > RSSI_dBm= RSSI_VAL - 45 > > > > Regards > > Peter > > On Tue, 2011-04-19 at 11:44 +0200, Miklos Maroti wrote: >> Hi! >> >> Look at the RF230ActiveMessageC component, and there you will see the >> PacketRSSI interface. Also, read the README in tos/chips/rf230 >> directory. You can either obtain the LQI or RSSI, but not both on the >> IRIS. As for the conversion, use the datasheets of the AT86RF230 and >> CC2420 radios to figure it out. >> >> Miklos >> >> On Tue, Apr 19, 2011 at 10:08 AM, CELALETTIN UMIT BAS <[email protected]> wrote: >> > Hello, >> > >> > I have problem on reading LQI and RSSI values from a iris mote. In one >> > of my application I was using RSSI and LQI values. I used to use >> > shimmer motes with tinyos. Both of LQI values were provided in >> > CC2420Packet interface with the functions of getRssi and getLqi. But >> > now I am trying to use same application on a iris motes from crossbow. >> > But I am not able to find the same interface or any interface >> > suggesting LQI and RSSI values. I found variables as strength and lqi >> > on TOS_MsgPtr. But these provides numbers in a different(ie. LQI in >> > shimmer (50,100), LQI in iris (0,255)) range than before. Is there any >> > conversion formula from one to another or should I read these values >> > from somewhere else on iris. >> > >> > Thanks in advance... >> > >> > C. Umit Bas >> > Graduate School of Sciences & Engineering >> > Electrical and Computer Engineering >> > M.Sc. Student >> > _______________________________________________ >> > 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 > > > _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
