Square wave output using fmcdaq2

Hi,

I'm confused, ad9144 is a high speed dac (1GSPS), why do you want it to output a squarewave of 1KHz?
The daq2 board has some filters on the output, you will have to change those to be able to transmit a sqare wave.

Take a look at https://ez.analog.com/fpga/f/q-a/81027/daq2-kcu105-send-data-to-dac

Are you familiar with our RF designs? If not, it may be of interest to you.

www.analog.com/en/products/adrv9008-2.html

www.analog.com/.../ad9361.html
wiki.analog.com/.../adrv936x_rfsom

Andrei

Thank you，Andrei

I am sorry for confusing you．I wanted to generate a square wave of 1 kHz because the modulator used operates by inputting a square wave of about 1 kHz to 2 kHz.

However, since the ADC/DAC I have is fmcdaq2, I would like to know haw to output a 1 kHz Square wave using fmcdaq2.

I'm sorry. I looked at https://ez.analog.com/fpga/f/q-a/81027/daq2-kcu105-send-data-to-dac and I saw the URL and could understand changing the filter of fmcdaq2, but I could not understand which part to change specifically.

Please tell me．

Yuta

Hi Yuta,

The axi_ad9144_core runs at 250 MHz for maximum sampling rate (1GHz), this means to keep up with the DAC you must have 4 parallel data paths.

I see some strange errors in your code.
This is a diff to something I've written, that has built successfully.

diff --git a/library/axi_ad9144/axi_ad9144_channel.v b/library/axi_ad9144/axi_ad9144_channel.v
index 75635a40..5a93392c 100644
--- a/library/axi_ad9144/axi_ad9144_channel.v
+++ b/library/axi_ad9144/axi_ad9144_channel.v
@@ -82,6 +82,10 @@ module axi_ad9144_channel #(
   reg     [15:0]  dac_dds_incr_0 = 'd0;
   reg     [15:0]  dac_dds_incr_1 = 'd0;
   reg     [63:0]  dac_dds_data = 'd0;
+  reg     [15:0]  square_wave_0 = 'd0;
+  reg     [15:0]  square_wave_1 = 'd0;
+  reg     [15:0]  square_wave_2 = 'd0;
+  reg     [15:0]  square_wave_3 = 'd0;
 
   // internal signals
 
@@ -176,7 +180,7 @@ module axi_ad9144_channel #(
       pn7 = dout;
     end
   endfunction
-  
+
   // PN15 function
 
   function [63:0] pn15;
@@ -266,7 +270,7 @@ module axi_ad9144_channel #(
       4'h6: dac_data <= dac_pn7_data_s;
       4'h5: dac_data <= dac_pn15_data_i_s;
       4'h4: dac_data <= dac_pn7_data_i_s;
-      4'h3: dac_data <= 64'd0;
+      4'h3: dac_data <= {square_wave_3,square_wave_2,square_wave_1,square_wave_0};
       4'h2: dac_data <= dma_data;
       4'h1: dac_data <= { dac_pat_data_2_s, dac_pat_data_1_s,
                           dac_pat_data_2_s, dac_pat_data_1_s};
@@ -286,6 +290,13 @@ module axi_ad9144_channel #(
     end
   end
 
+  always @(posedge dac_clk) begin
+    square_wave_0 <= {16{dac_dds_phase_0_0[15]}};
+    square_wave_1 <= {16{dac_dds_phase_1_0[15]}};
+    square_wave_2 <= {16{dac_dds_phase_2_0[15]}};
+    square_wave_3 <= {16{dac_dds_phase_3_0[15]}};
+  end
+
   // dds
 
   always @(posedge dac_clk) begin
@@ -331,7 +342,7 @@ module axi_ad9144_channel #(
     .dds_data (dac_dds_data_0_s));
   end
   endgenerate
-  
+
   generate
   if (DATAPATH_DISABLE == 1) begin
   assign dac_dds_data_1_s = 16'd0;
@@ -346,7 +357,7 @@ module axi_ad9144_channel #(

Can you compare what you have whit this, and let me know if have questions about it.

Andrei

Hi, Andrei

I made corrections with reference to your program.
As a result of building, I succeeded in building.

I ran it with SDK in the same way as before.

Then the following waveform was output.
It was a waveform that was not  the square wave.

What should I do?

Yuta

Hi,

Have you simulated the code?
At what frequency have you set the DDS, try more frequency ranges....
What changes have you done to the analog side of the daq2?

Andrei

Hi,

I simulated the code.

The result is shown below." reg [15: 0] increment " is assigned 'd1.

The picture I placed before was 1 GHz.

There was nothing in the UART message.

The figure below is at 500 MHz.

The figure below is for 600 MHz.

Furthermore, as increment, the same waveform was output as the result of building with dac_dds_incr_ 0 = 'd 0; with dac_dds_incr_ 0 =' d 1; of axi_ad9144_channel.v.

The analog part has not changed anything. It connects directly to the oscilloscope from the SMA of fmcdaq 2 and outputs it.

Yuta

Furthermore, change the increment to dac_dds_incr_ 0 = 'd 0 to dac_dds_incr_ 0 =' d 1 of github.com/.../hdl_2018_r 1/library/axi_ad 9144/axi_ad 9144 _channel.v # L 82, and the result of outputting the waveform , A similar waveform was output. Is this correct? Z

The above URL was here ：　https://github.com/analogdevicesinc/hdl/blob/hdl_2018_r1/library/axi_ad9144/axi_ad9144_channel.v#L82

Also, the waveform at 500 MHz was shown below. I'm sorry.

Hi,

You are changing the sampling rate, I was referring to the DDS frequency.

github.com/.../fmcdaq2.c
github.com/.../fmcdaq2.c

Andrei

Hi，

How do I change github.com/.../fmcdaq2.c the sampling rate?

Although it lowered, it did not work well and an error appeared.

Also, although the DDS was set to a lower frequency, the same waveform was output. We tried at multiple frequencies (eg 1 Hz, 1 kHz, 1 MHz etc) but the waveform did not change at all. What could be the cause?

Yuta

Hi,

Yes, the magic happens here https://github.com/analogdevicesinc/no-OS/blob/master/fmcdaq2/fmcdaq2.c#L105-L235

Use the DDS (sinewave), look at those signals do things change?
The filter on the output of daq2 not being designed for squarewave signals.

Andrei

I tried various things. As a result, the waveform output as shown below was obtained.
Thank you very much.

Things like oscillation can be seen in the HIGH part, is this due to the  filter on daq2?

I tried various things. As a result, the waveform output as shown below was obtained.
Thank you very much.

Things like oscillation can be seen in the HIGH part, is this due to the  filter on daq2?

Hi,

As a result of further trials, the oscillating part disappeared. Thank you very much.

Yuta

Hi,

Out of curiosity, why have you insisted on using the ad9144's output for a low-frequency square wave, taking into consideration the physical changes that had to be made?

Andrei

Hi, Andrei.

It was necessary to be low frequency due to the relationship of the devices used for the current communication system.
In the future, when the performance of the device improved and it became possible to cope with high frequencies, I wanted to be able to vary only the frequency without changing the environment to use.

Yuta

Hi Yuta,

we are also using the AD9144 DAC for Square wave conversion, we are also facing the oscillation part.

Could you please let us know how did you solve this?

Regards,

Poornima