CS-LIME-26 (LimeSDR Mini 2.0) is defective

[usman.niazi]

Hello Team,

One of our customers purchased CS-LIME-26 and claim part is defective. They provided following information,

---

One of the parts—in this case, the “LimeSDR Mini 2.0”—is “defective,” though the focus here should be on limited functionality rather than a hardware defect. There was no damage to the part or the packaging that could have caused the defect.

After a driver update (USB reset following the LimeSDR update with the LimeSDR connected), the LimeSDR Mini 2.0 is no longer recognized. I noticed this because the RX and TX LEDs were flashing red intermittently along with the standby LED. A subsequent test with the LimeSuite software revealed that the USB driver was loaded, the device was recognized as “unknown” with FW 6 and a 40 MHz clock, but no further functions were available.

However, the LimeSDR is recognized by SDR-Cube. Since SDR-Cube uses its own FX3 communication protocol, the device (bootloader, FPGA, etc.) isn’t classically defective; rather, an incorrect firmware version was likely installed during the automatic update, which no longer allows operation with my applications.

However, while searching for the latest firmware downloads, I discovered that they are not available. Furthermore, I learned that this appears to be a common problem when updating the LimeSDR Mini 2.0, usually resulting in the bootloader being corrupted.

There is no visible external damage. If you need a hard copy or a photo of the conditions described above, I will provide it to you. For safety reasons—to prevent further damage to the device—I have disconnected it and have not put it back into operation to date; however, I would need to do so.

I hope the information provided has given you an understanding of the item’s defect, and I hope that you or your team will be able to assist me further.

-------------------------

Could you please review the information provided by the customer and confirm whether the part appears to be defective? Additionally, are there any troubleshooting steps or recommendations that could help the customer resolve the issue?

Best,

Usman

[VytautasB]

Hi,

this looks like an unsuccessful/incompatible update resulted in corrupted FPGA gateware, rather than a hardware defect.

-At this point, recovery will most likely require reprogramming the FPGA through JTAG cable.

-Please provide the exact software, version, and update procedure that was used.

-Was it working before update?

-Can you see any LED activity when board is connected to USB3.0 port?

-Is board detected with lsusb on linux or Device manager on Window?

Regards,
Vytautas

[usman.niazi]

Hello, please see following customer response,

---

---

---

--

Thank you for providing the technical information from your support team. Attached you will find a complete and precise response to all inquiries, including five additional images documenting the device behavior. Before addressing the technical findings, I must explicitly state the following:I am an end user and not a technician or IT specialist. Any procedure requiring specialized programming hardware, firmware reconstruction, JTAG
flashing, or comparable interventions exceeds what can reasonably be expected
from an end user under warranty or statutory guarantee obligations. For this
reason, I must formally decline any such measures.

Initial situation Hardware: LimeSDR Mini 2.0 (1DBB748D3F1CF8)

                            Raspberry Pi 5, 8 GB

                            SSD Crucial P3, 500 GB

                Software:    Raspberry Pi OS Trixie Light (x64)

                Application: TMO Mini Base StationDuring stable operation, the standby LED was green, the RX LED green, and the TX LED red. Following a software‑related adjustment, an update was executed using <LimeUtil --update>. Immediately after this update, the standby LED began alternating between green and red, while the RX/TX LEDs remained off. Changing USB3 ports did not resolve the issue. The same procedure was repeated on both ports, consistently resulting in <No devices found>. The commands <lsusb> and <SoapySDRUtil --find> were executed; results are shown in image 1.Using Lime Suite GUI under Linux (accessed remotely), the LimeSDR Mini 2.0 could not be detected, see image 2.The device was then tested on a Windows 11 PC. Drivers were installed, LimeSuite for Windows was launched, and the device was accessed. The following status was displayed: Connected Control Port: UNKNOWN FW:6 HW:7 Protocol:1 GW:2.2 Ref Clk: 40.00 MHz. A temperature query returned 41°C. After selecting the Default tab and starting FFTviewer, limited activity was visible, see image 3. The operating LED blinked green; the RX LED remained steadily green.CubicSDR (image 4) recognized the device, but the operating LED alternated between green and red. RX LED remained green.SDR++ detected the device but could not produce any operational output, see image 5.**Formal Technical Assessment:**

Based on the documented behavior, the FX3 controller appears to have loaded a fallback firmware during the update process instead of the correct LimeSDR Mini 2.0 firmware. This fallback firmware is only partially functional. It allows:

• USB communication
• LMS7002M addressing
• RX path initialization
• Frequency configuration
• Data packet transfer

However, LimeSuite cannot communicate with the device because the FX3 is not running the correct firmware. This explains the “UNKNOWN” status. The FX3 is evidently stuck in bootloader mode and therefore unable to operate or flash the FPGA (JTAG). A correct FX3 image file for the LimeSDR Mini 2.0 would be required to restore proper functionality. Such an image is not publicly available, and reprogramming the FX3 controller cannot be reasonably expected from an end user under warranty conditions.Furthermore, it is uncertain whether full functionality could be restored even if such reprogramming were attempted. This is clearly a firmware mismatch originating
from the FX3 subsystem, not an FPGA gateware configuration error.

Formal Conclusion and Warranty Request:

Given the above findings, the device is no longer operational after a standard update procedure and cannot be restored to proper working condition using end‑user‑appropriate methods. The malfunction is reproducible, documented, and technically attributable to the device’s firmware subsystem.For these reasons, I must formally request a warranty remedy in accordance with applicable consumer protection and warranty regulations. If reprogramming the FX3 controller cannot be performed by the manufacturer with guaranteed success, a replacement
of the hardware is the only appropriate and necessary solution.I kindly ask you to initiate the corresponding warranty or RMA process.

[VytautasB]

From the provided Windows screenshot, LimeSuite is able to read the firmware and gateware versions, and an active data stream is also visible. Based on this, the device appears to be operational.

Also to note LimeSDR Mini v2 does not use an FX3 controller. it uses FT601, so there is no FX3 firmware or FX3 bootloader on this device.

The device being reported as UNKNOWN may indicate that an unsupported or older LimeSuite version is being used. LimeSDR Mini v2 support was added starting from LimeSuite v22.09.0.

Could you please provide the exact LimeSuite version used on Windows? Open LimeSuiteGUI → Help → About and provide a screenshot of that window.

Please also provide the exact LimeSuite/LimeSuiteGUI version used on the Raspberry Pi, and confirm which LimeSuite version was used when the update was attempted.

At this point, I do not see clear symptoms of a hardware failure. Based on the information provided so far, this looks more like a software compatibility/version issue, so I would first verify the LimeSuite versions.