# LimeSDR Mini V2 reading samples from RX FIFO

**URL:** <https://discourse.myriadrf.org/t/limesdr-mini-v2-reading-samples-from-rx-fifo/7900>\
**Category:** LimeSDR\
**Created:** [21 March 2023 08:00 UTC](https://discourse.myriadrf.org/t/limesdr-mini-v2-reading-samples-from-rx-fifo/7900 "2023-03-21T08:00:16Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![sergey](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/sergey/32/4871_2.png) [@sergey](https://discourse.myriadrf.org/u/sergey)\
**Post date:** [21 March 2023 08:00 UTC](https://discourse.myriadrf.org/t/limesdr-mini-v2-reading-samples-from-rx-fifo/7900/1 "2023-03-21T08:00:16Z")

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Hello everyone,

I am running into an interesting quirk with the LimeSDR Mini V2.0: `LMS_RecvStream()` times out and returns nothing until either of the following is done:

- The `LMS_SetLPFBW()` is called after the `LMS_StartStream()`, or
- The transmit channel is enabled `LMS_EnableChannel(device, LMS_CH_TX, 0, true)`

Initially I’ve run into this issue when attempting to use SDR++, but seems the same behavior is easy to reproduce with the `singleRX` example from the LimeSuite.

Using the LimeSuit from the current latest Git (hash 38efe960). Building it and running the `singleRX` ends up in `RX data rate: 0 MB/s` and `RX fifo: 0%` printed every second. If the transmit channel is enabled right after the receive channel, then the data is properly received and logs are then state `RX data rate: 32.1454 MB/s`.

It is a bit hard for me to tell for sure, but it seems that the `LimeSuiteGUI` experiences similar problem of not receiving data. At least I’ve run several times into situation when the configuration looks fine, but the fftViewer does not show anything until something is re-configured in the interface. That was with 22.09 version, did not have chance to dig into the GUI from the latest Git yet.

The `LimeQuickTest` succeeds, and the `basicRX` is working as well (the latter one has an explicit code which enables TX channel for the v2).

For the details of the software/hardware:

```auto
->LimeSuite version: 22.09.1-g38efe960
->Device: LimeSDR Mini, media=USB 3.0, module=FT601, addr=24607:1027, serial=1D90EBBA46D10C, HW=5, GW=2.1

```

What is the correct/expected behavior and the usage of API?  
Is it something that could/will be fixed with the next version of the gateway? Or, shall the software to enable both RX and TX channels even for the RX-only usage?

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**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:** [21 March 2023 12:03 UTC](https://discourse.myriadrf.org/t/limesdr-mini-v2-reading-samples-from-rx-fifo/7900/2 "2023-03-21T12:03:21Z")

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> [@sergey](#):
>
> Or, shall the software to enable both RX and TX channels even for the RX-only usage?

Yes, you have to enable both RX and TX channels even only RX is used. This is because of gateware implementation.

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**Author:** ![sergey](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/sergey/32/4871_2.png) [@sergey](https://discourse.myriadrf.org/u/sergey)\
**Post date:** [24 March 2023 17:42 UTC](https://discourse.myriadrf.org/t/limesdr-mini-v2-reading-samples-from-rx-fifo/7900/3 "2023-03-24T17:42:26Z")

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Thanks for the information!

There is one thing which got me confused a bit. Does enabling TX channel (without creation of the TX stream) affect on the amount data transferred via USB?

As in, does the `LMS_EnableChannel(device, LMS_CH_TX, 0, true)` lead to transfer of data from the host computer to the LimeSDR radio? Or is the transfer to the radio is only actually happening when `LMS_SendStream` is used?

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<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:** [11 May 2023 08:22 UTC](https://discourse.myriadrf.org/t/limesdr-mini-v2-reading-samples-from-rx-fifo/7900/4 "2023-05-11T08:22:38Z")

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> [@sergey](#):
>
> Does enabling TX channel (without creation of the TX stream) affect on the amount data transferred via USB?

It doesn’t affect amount of data transferred via USB. It just enables required clock.

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**Author:** ![sergey](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/sergey/32/4871_2.png) [@sergey](https://discourse.myriadrf.org/u/sergey)\
**Post date:** [12 May 2023 20:58 UTC](https://discourse.myriadrf.org/t/limesdr-mini-v2-reading-samples-from-rx-fifo/7900/5 "2023-05-12T20:58:14Z")

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Thanks for the clarification! 🙂