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Question asked by Domenico Virgilio on Mar 15, 2019
Latest reply on Mar 27, 2019 by Estephania Martinez


we need to perform a CCA using GENFSK.

From the datasheet we saw that the CCA treshold is supported only in the ZLL, but we want to put a treshold in software to compare with ED value.

In the documentation of the Receiver Digital Module in MKW41Z Reference Manual (page 1673), is reported that the Digital Module can return the ED value from the rx_cca_ed_lqi which, in turn, uses the w/rssi signal from rx_agc Module.

So we supposed, following the manual, that we can use XcvrFskGetInstantRssi test function provided in MCUXPRESSO_SDK v 2.2.0 to perform an RX WarmUp, read the XCVR CCA_ED_LQI_STAT_0 register and get the ED value, but this approach doesn't work.

The table 45-20 (page 1686 - Reference Manual) shows the two signals which needs to be configured to raise CCA1/ED
meas. state (wideband mode). The signal cca1_ed_trig should be triggered on RX WarmUp, the second one, sfd_aa_match, has no references in the Reference Manual.

So the questions are:

1) It's possible to use RSSI/CCA1/LQI module in direct manner using the Receiver Digital Module and it's registers, without using the ZLL Module registers?


2) If not, is there a way to software compute the ED, starting from the istant RSSI value?


We think that once computed the ED, we can address in our firmware a CCA threshold value and design a CA strategy to avoid collisions.

Have you any hint which can put us on the right path?


Best Regards,


Domenico Virgilio