MCU error 5 (Loopback signal weak: not connected/insufficient gain?)

General Discussion
1

Hi all,
I have been using a Lime SDR mini along with GNU Companion for a while without no problem. But suddenly, I always get this message when I run my GNU design:

Tx Calibration: MCU error 5 (Loopback signal weak: not connected/insufficient gain?)

Could it be that my Lime SDR mini has been deteriorated? Can it be fixed? I have used Lime SDR Suite without any success…

Please Helpppp

2

Please run LimeQuickTest and post the results, ensuring that nothing is connected to the RF ports and the board is cold when you do this.

3

Hi Andrew,
thank you very much for your quick answer. Here is the outcome

[ TESTING STARTED ]
->Start time: Tue Feb 23 08:53:18 2021

->Device: LimeSDR Mini, media=USB 2.0, module=FT601, addr=24607:1027, serial=1D538A0705FFD2, HW=2, GW=1.30
Warning: USB3 not available
Serial Number: 1D538A0705FFD2
Chip temperature: 25 C

[ Clock Network Test ]
->REF clock test
Test results: 33104; 46301; 59499 - PASSED
->VCTCXO test
Results : 6710985 (min); 6711141 (max) - PASSED
->Clock Network Test PASSED

[ FPGA EEPROM Test ]
->Read EEPROM
->Read data: 13 07 0C 13 07 0C 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:(-15.1 dBFS, 5.00 MHz) - PASSED
->Run Tests (TX_1 → LNA_H):
CH0 (SXR=2100.0MHz, SXT=2105.0MHz): Result:(-14.6 dBFS, 5.00 MHz) - PASSED
->RF Loopback Test PASSED

=> Board tests PASSED <=

Elapsed time: 2.72 seconds

4

Could you save register ini file when this calibration fails and share it, please.