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ADF7021-N,RSSI level always 0.Where is my error?

Question asked by Diegotrex on Jan 15, 2013
Latest reply on Jan 15, 2013 by enash

Hi to everybody in this forum,

thanks in advance just for reading this


My firmware is not able to read RSSI level on ADF7021-N mounted on a specific board


The board itself can be connected to the Eval board,and in this case RSSI can be read,

It is pretty correct,i.e -60dBm RSSI vs -59 dBm on a very good spectrum analyzer.

So i can guess that my hardware  works fine.


If i control the ADF7021 by means of a uC i can succesfully set the Tx frequency,i  have correct readback of VDD,Product Id(0x2111),external ADC IN but RSSI remains 0x500..

To have something different i have to let ADC disabled in register 8:I this case i have RSSI=0x52F ,changing signal level has not effect.


I use the EVB as a Tx,generating  a modulated signal,say 100MHz at2,4Kbps 1010 GFSK.

The Rx is my bord,


i set at 170Mhz Rx mode(synth dividers calculated 100KHz lower,169.90 Mhz), MUXOUT set to digital lock,i wait for it going high(in Tx it works)


then i perform the readback in the following steps

1)ADC Enable setting bit 8 of register 8   (0x108)

2)Setting value to write in Readback setup register :Readback for ADC out and ADC converting RSSI,Readback enabled

3)I write the above value(0x147) in Register 7 ,Readback Setup Register

4)I set register 0 to have RSSI_Ready  signalled on MUX_OUT ,

5)I wait until RSS_ Ready is high,but it it looks always high,..why?

6)I perform the Readback in 18 clock cycles

7)I turn off ADC


Thanks again for your attention