Adding fft in fpga resulting in CODEC loopback test failed

[dheller26]

hello everyone ,
i'm using the b205mini usrp and I need to implement a fft block on the fpga inside the usrp and pc gets the data in freq domain. I designed my fft using xilinx IP core ver 7.1 and place it in the top module after the b205_io module using it's 12 bits I & Q ports .
unfortunately when testing my design in gnuradio i got ERROR CODEC loopback test failed as you can see below.

what can be the problem ? when my design is clean without fft i don't get errors like that .
i will appreciate your help.
with best regards .
Dror

[mbr0wn]

If you want to put the FFT before b205_io then you need to disable the codec loopback in the UHD driver. Probably much easier to stay on the other side of radio_legacy and work on the rx_t* signals (AXI-stream).