# usrp\_b210\_GRC=\>RuntimeError: CODEC loopback test failed

**URL:** <https://www.ruby-forum.com/t/usrp-b210-grc-runtimeerror-codec-loopback-test-failed/261425>\
**Category:** GNU Radio\
**Created:** [June 20, 2021, 4:45am UTC](https://www.ruby-forum.com/t/usrp-b210-grc-runtimeerror-codec-loopback-test-failed/261425 "2021-06-20T04:45:01Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![taha.zand](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/b9bd4f/32.png) [@taha.zand](https://www.ruby-forum.com/u/taha.zand)\
**Post date:** [June 20, 2021, 4:45am UTC](https://www.ruby-forum.com/t/usrp-b210-grc-runtimeerror-codec-loopback-test-failed/261425/1 "2021-06-20T04:45:02Z")

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Hi all

I’m a SDR beginner and i have a usrp b210. 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 and place it in b200\_io module where input data (12-bit rx\_data) convert to i-q signal (12-bit rx\_i, rx\_q) but i got runtime error.(codec loopback test failed).

please help me to solve this problem.

Thanks.

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**Author:** ![msdr\_boy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/a4c791/32.png) [@msdr\_boy](https://www.ruby-forum.com/u/msdr_boy)\
**Post date:** [May 12, 2024, 12:28pm UTC](https://www.ruby-forum.com/t/usrp-b210-grc-runtimeerror-codec-loopback-test-failed/261425/2 "2024-05-12T12:28:00Z")

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hello taha,  
i got the same problem and i wondered if you happen to find a solution to this ? i also use fft after the b205\_io module and got the same error when testing it on gnuradio