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272 Views
Registered: ‎06-18-2019

[ZCU111] How to connect LMX2594 to RFDC dac_clk

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I am attempting to run a simple design where I output a signal from a single DAC on the ZCU111. This design is based on the RFDC IP example design, but uses the Zynq processor so that interfacing with a PC GUI is not needed.

I want to clock the DAC using the LMX2594, but I cannot seem to find connection PIN specifications anywhere to connect the top level "dac1_clk" port to it.

rfdc_ex.PNG

(I know there are some issues with the reset in that screencap. I fixed it.)

 

I have also read that I will need to program the LMX2594, which I assume I can accomplish with the Zynq, but again, I cannot find specifications for how to connect an interface for programming it.

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207 Views
Registered: ‎06-18-2019

Re: [ZCU111] How to connect LMX2594 to RFDC dac_clk

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It seems that the solution to this is "you don't."

If you just set the rfdc clocks to be external and don't set constraints (or even include them in your top-level design file, for that matter), vivado will just magically connect everything. The same applies for the I2C interface that controls the LMX. You just enable I2C on the Zynq processor and it is connected behind the scenes.

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Registered: ‎06-18-2019

Re: [ZCU111] How to connect LMX2594 to RFDC dac_clk

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I think that I have found the PIN connections for the clock outputs in the ZCU111 schematic, but I can't help but feel like I am not taking the correct approach.

zynq_banks.PNG

Even if this is the correct way to hook up the outputs, I still do not know how to connect the LMX to the Zynq processor for configuration.

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208 Views
Registered: ‎06-18-2019

Re: [ZCU111] How to connect LMX2594 to RFDC dac_clk

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It seems that the solution to this is "you don't."

If you just set the rfdc clocks to be external and don't set constraints (or even include them in your top-level design file, for that matter), vivado will just magically connect everything. The same applies for the I2C interface that controls the LMX. You just enable I2C on the Zynq processor and it is connected behind the scenes.

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Observer nicolas05
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Registered: ‎06-05-2019

Re: [ZCU111] How to connect LMX2594 to RFDC dac_clk

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Hi @dclaymidkiffnasa ,

 

I would like to know where can I find that example. What is the advantage of using this instead of the GUI? I'm trying to run an analog square wave generator but I don't know what is the best method.

 

Thanks!

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123 Views
Registered: ‎06-18-2019

Re: [ZCU111] How to connect LMX2594 to RFDC dac_clk

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If you drop an RFDC block in the block designer in an existing project, customize it with all the DACs/ADCs you want, and then right click on the block, there will be an option called something like "Open IP Example Design," which will generate an example project for you.

 

I will warn you, though, I never got the DAC Source block in their example design working. It requires programming over AXI, but the addresses and required configurations are poorly documented. If you haven't, I would recommend looking at the RF Data Converter LogiCore IP Guide. What limited documentation there is of the example design is in there, plus a bunch of information on RFDC in general.

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Registered: ‎06-18-2019

Re: [ZCU111] How to connect LMX2594 to RFDC dac_clk

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The advantage for me of using this over the GUI is that I want to develop actual embedded firmware that will run without having to interact with a GUI each time. I need to do GPS signal acquisition and processing on the FPGA, and there is little interest in an instrument that requires you manually configure the hardware components via proprietary GUI each time you turn it on.

 

If you are just looking to do a square-wave demo, you may be fine using the GUI. You should be able to pretty easily replace the DAC Source, though, if you do go the manual route, as a square wave is super simple to generate.

Observer nicolas05
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Registered: ‎06-05-2019

Re: [ZCU111] How to connect LMX2594 to RFDC dac_clk

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Thank you @dclaymidkiffnasa !

 

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Observer nicolas05
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Registered: ‎06-05-2019

Re: [ZCU111] How to connect LMX2594 to RFDC dac_clk

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Hi @dclaymidkiffnasa ,

I also need to generate any waveform by driving the DACs in the board.

In the screen cap there is an IP block with the name of "dac_source_i". I could not find it in the "Add IP" option in Vivado 2018.3. I believe that block is in charge of driving an input digital wave to the DAC so the corresponding analog waveform is generated, right? If so, where can I download it and read about how it works?

I can not access to the IP Example Project of the RF Data Converter (still do not find the reason), therefore I am not aware of the blocks inside it.

Thanks!

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