LimeSDR Mini Loopback Test Fail and Rx Calibration Fail

Projects LimeSDR
1

Hello, my recently purchased LimeSDR Mini intermittently fails the limequicktest Loopback Test. I’ve tried with and without an antenna, and with the device relatively cool and after it’s been on for a while. Also, Rx calibration (using SDRConsole v3) sometimes fails, with this message: “Rx calibration: MCU error 5 (Loopback signal weak: not connected/insufficient gain)”.

Some additional information:

Firmware: 6
Hardware: 3
Protocol: 1
Gateware: 1.3

Output from limequicktest:

[ TESTING STARTED ]
->Start time: Sat Feb 8 20:08:34 2020

->Device: LimeSDR Mini, media=USB 3, module=FT601, serial=1D588FCCD7CB77, index=0
Serial Number: 1D588FCCD7CB77

[ Clock Network Test ]
->REF clock test
Test results: 54511; 2172; 15369 - PASSED
->VCTCXO test
Results : 6711019 (min); 6711186 (max) - PASSED
->Clock Network Test PASSED

[ FPGA EEPROM Test ]
->Read EEPROM
->Read data: 13 0A 16 13 0A 16 02
->FPGA EEPROM Test PASSED

[ LMS7002M Test ]
->Perform Registers Test
->External Reset line test
Reg 0x20: Write value 0xFFFD, Read value 0xFFFD
Reg 0x20: value after reset 0x0FFFF
->LMS7002M Test PASSED

[ RF Loopback Test ]
->Configure LMS
->Run Tests (TX_2 -> LNA_W):
CH0 (SXR=1000.0MHz, SXT=1005.0MHz): Result:(-57.3 dBFS, 2.54 MHz) - FAILED
->Run Tests (TX_1 -> LNA_H):
CH0 (SXR=2100.0MHz, SXT=2105.0MHz): Result:(-13.1 dBFS, 5.00 MHz) - PASSED
->RF Loopback Test FAILED

=> Board tests FAILED <=

Elapsed time: 3.43 seconds

Wondering if the board has a hardware issue, or ? Any guidance would be greatly appreciated!

2

I face exactly the same issue with LimeQuickTest. I’m using Linux so I dont know how SDRConsole would behave.
When I blow air on it with my Arctic usb fan, it recovers and will consistenly pass the tests. It looks like a heat issue.
Lime Microsystems have not yet confirmed if this is exepted and if the results make sense.

3

Thanks for the info. I gave it a try (I put a large fan right next to my Lime) but unfortunately it had no effect for me, loopback test failures persisted. Still waiting to hear from Lime Microsystems…

4

Hi @kend1

Do you have something connected to the RF ports during test procedure? If yes, then disconnect it and repeat the test. Otherwise check with Crowd Supply if RMA is applicable.

Yes, it makes sense. As I mentioned many times before, Quick Test is tuned for cold board. And yes, it is desired to have cooling solution for it.

5

Thanks @Zack. Nothing connected to the RF ports, I’ll check with Crowd Supply re an RMA. FWIW the reported temperature ranges from 38-45 C (with a large fan).

6

Here’s my test results:

[ RF Loopback Test ]
->Configure LMS
->Run Tests (TX_2 -> LNA_W):
CH0 (SXR=1000.0MHz, SXT=1005.0MHz): Result:(-19.7 dBFS, 5.00 MHz) - PASSED
->Run Tests (TX_1 -> LNA_H):
CH0 (SXR=2100.0MHz, SXT=2105.0MHz): Result:(-20.5 dBFS, 5.00 MHz) - FAILED
->RF Loopback Test FAILED

=> Board tests FAILED <=

LimeSuite version: 20.10.0-g1480bfea
HW=3
GW=1.30
Chip temperature: 20 C

7

Wowww passed with Chip temperature: -5 C

[ RF Loopback Test ]
->Configure LMS
->Run Tests (TX_2 -> LNA_W):
CH0 (SXR=1000.0MHz, SXT=1005.0MHz): Result:(-18.6 dBFS, 5.00 MHz) - PASSED
->Run Tests (TX_1 -> LNA_H):
CH0 (SXR=2100.0MHz, SXT=2105.0MHz): Result:(-19.1 dBFS, 5.00 MHz) - PASSED
->RF Loopback Test PASSED

=> Board tests PASSED <=