# XTRX not found

**URL:** <https://discourse.myriadrf.org/t/xtrx-not-found/8386>\
**Category:** LimeSDR\
**Created:** [20 July 2024 13:52 UTC](https://discourse.myriadrf.org/t/xtrx-not-found/8386 "2024-07-20T13:52:51Z")\
**Posts on this page:** 1\
**Showing post:** 28

<div class="post-metadata">

**Author:** ![Zack](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/zack/32/89_2.png) [@Zack](https://discourse.myriadrf.org/u/Zack)\
**Post date:** [4 August 2025 09:08 UTC](https://discourse.myriadrf.org/t/xtrx-not-found/8386/28 "2025-08-04T09:08:30Z")

</div>

In LimeSDR XTRX v1.2 BOM\_VER = 0 boards and earlier versions, the PERST control was not properly implemented.

As a workaround, soldering a 0-ohm resistor at R114 offers a simple solution, though it is not ideal. In this case, the PERST signal directly controls the entire board’s power supply, which is suboptimal and should be avoided.

**The correct approach** is to use the PERST signal to properly control the PCIe core within the FPGA. This issue was resolved in LimeSDR XTRX v1.2 BOM\_VER = 1 and later versions by modifying the BOM. **In these updated boards, R114 remains unsoldered**.

To visually identify the BOM version of a LimeSDR XTRX v1.2 board, check resistor R49 as shown in the picture below. If R49 is not populated, the board is BOM\_VER = 1, indicating that the PERST circuit is correctly implemented and no further action is needed.

 ![image](https://canada1.discourse-cdn.com/flex034/uploads/myriadrf/original/2X/9/9a09f179f7676c83f85da1a7d7589f63e0995f44.jpeg)

**More information can be found here:** [https://limesdr-xtrx.myriadrf.org/v1.2/#bom-version-1-bom-ver-1](https://limesdr-xtrx.myriadrf.org/v1.2/#bom-version-1-bom-ver-1 "https://limesdr-xtrx.myriadrf.org/v1.2/#bom-version-1-bom-ver-1")

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