Need help with LMS7002M EVB

[Krushi Deep]

Hi, 

I am currently working with the LMS7002M I am trying to use the digital loop back through the limelight block.I was able to control the Tx and Rx chain independently. 

I want to take an input signal from Rx input up/down convert the signal to baseband then take it to the TxTSP through the limelight using the digital loop back via the Tx FIFO to the Tx pad. 

how do i get this going? 

following picture shows the signal path that I intend to take the signal through.

Regards

Krushi

[Ricardas Vadoklis]

Hello,

Try attached register setup file. It will also set transcievr to operate from single TxPLL. Tx PLL frequency 1850 MHz

Best,
Ricardas

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[Krushi Deep]

Hi Richards,

Thanks for your quick response, I tried this *.ini file and this is the procedure I followed 

1. Connected the GUI to board com port
2. opened the *.ini file using the GUI
3. downloaded the reg data using GUI-->Chip
4. selected SXT/SXR 
5. Deselected both from the configuration channels - calculate and tune independently

is this procedure right? 

What is the expected output? I see Rx tuned to 800MHz , Tx tuned to 1.85GHz and NCO @ 5MHz so i was expecting a 1GHz signal at the output is my understanding right.

I was not able to tune the Rx VCO majority of the times unless i dint enable the SXT/SXR in the power down group controls.

So having said all this. here is what I actually intend to do.

1. Feed an input signal (845MHz) to the Rx LNAH channel and mix it with the VCO (850 MHz) 
2. Bypass the RxTSP 
3. Digital loopback in limelight i.e, RxTSP input to the TxTSP via Tx FIFO 
4. Tune the NCO (20MHz) 
5. Bypass VCO and monitor the output on Tx-A pad.

Is this feasible? Is so How do i do this?

Regards 

Krushi

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[r.vad...@limemicro.com]

Hello Krushi,

You have all this configuration in the file I've sent to you. Just change TxPLL frequency to 850MHz. 

LMS7002M has option to drive Tx and Rx path from single PLL, if your application requires. In this way you can save current. This is how registers were configured in the file I sent to you. 

‎Your procedure is good.

Best Regards,
Ricardas Vadoklis

From: Krushi Deep Sent: Sunday, 8 November 2015 11:00 To: Lime Microsystems open-source support channel Cc: r.vad...@limemicro.com Subject: Re: Need help with LMS7002M EVB

[Krushi Deep]

Hi Ricardas,

We used the .ini file you provided but i dont see the desired output (1GHz).

Since i was not sure if I was following the right procedure. we did the following experiments.

When we used the TxTSP test signal (Refclk/8) with NCO tuned to 20Mhz I see the output as expected (27.72 MHz).
with the reference clk freq  @ 61.44
 
Then we wanted to check if we can route the RxTSP test signal to the TxTSP, but i dint see any output at the Tx pad.

The other configurations that we changed are with the ADC and the DAC clocks to sync them up, ADC was provided with CLKH/4 and DAC was provided with CLKL/4 and we see the clocks are running at the correct freq (15.36MHz)

We think that there is some issue that we are running into with the RxTSP, so can you suggest a simple way by which i can verify the functionality of RxTSP and limelight independently.

Thanks

Regards
Krushi

[r.vad...@limemicro.com]

Hello Krushi,

See my comments below.

Best Regards,
Ricardas Vadoklis

From: Krushi Deep Sent: Monday, 9 November 2015 20:17

To: Lime Microsystems open-source support channel

Cc: r.vad...@limemicro.com; Deepak Kumar Chandrasekaran; kru...@traana.in; jo...@joshknows.com

Subject: Re: Need help with LMS7002M EVB

Hi Ricardas,

We used the .ini file you provided but i dont see the desired output (1GHz).

You should see LO output at 1850 MHz (TxPLL frequency setup).

Since i was not sure if I was following the right procedure. we did the following experiments.

When we used the TxTSP test signal (Refclk/8) with NCO tuned to 20Mhz I see the output as expected (27.72 MHz).
with the reference clk freq  @ 61.44

OK.‎

 
Then we wanted to check if we can route the RxTSP test signal to the TxTSP, but i dint see any output at the Tx pad.

The other configurations that we changed are with the ADC and the DAC clocks to sync them up, ADC was provided with CLKH/4 and DAC was provided with CLKL/4 and we see the clocks are running at the correct freq (15.36MHz)

We think that there is some issue that we are running into with the RxTSP, so can you suggest a simple way by which i can verify the functionality of RxTSP and limelight independently.

Please send me your register configuration file. I'll correct for you.

[Krushi Deep]

Hi Ricardas,

Please find the attached 2 files of the register configuration. I could not get the exact reg config files as we had off today for one of our regional fistivals ( Diwali - festival of lights) so i just made changes on the GUI without hardware and these are the files one for RxTSP test and the other for RxTSP Digital loop back.

Regards

Krushi

[Ricardas Vadoklis]

Hello Kruchi,

The main issue with your setup, is that you are trying to loopback Rx B channel to Tx A channel. This isn't going to work. You can set loopback ch A-> ch A.
 
I have attached register configuration for LMS7002M. This will setup TRx for internal Loopback mode. Receiver PLL frequency is set to 800MHz, transmitter is set to 1850MHz. Connect spectrum analyzer to X2 connector to EVB board, and signal generator to X6 connector.  Set generator frequency to 801MHz (signal level -60dBm), and you should see signal at 1849MHz on analyzer.

Please note, that you need to RETUNE RxPLL, TxPLL and CLKGEN to get wanted frequency.

Let me know if you do have any questions.

Best,
Ricardas Vadoklis

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