UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

cancel
Showing results for 
Search instead for 
Did you mean: 
Highlighted
Observer rica.soles
Observer
613 Views
Registered: ‎06-01-2018

Hi!

I'm workin in vivado and i have a problem with IP  DDS V.6. I do the conexion with clocking wizard to DDS IP. In the simulation is fine, i can see sine wave but i program the board nexys video, in the port (PMOD, JB and JC) when i check this port with a oscilloscope i don't see nothing only noise. I supose which i need see the signal each port.

 

dds_1.jpg                                   

 

In the next picture I do simulation. I think which in each port JB and JC i need see the signal as in simulation but i don't see nothing.

dds_2.jpg

any suggestions.

Thanks! regards.

0 Kudos
1 Solution

Accepted Solutions
542 Views
Registered: ‎06-21-2017

While I am not familiar with the Nexis Video board, the description leads me to believe that the PMODs are not connected to a Digital to Analog converter.  If you have a 3.3V logic signal changing 100 million times a second going through a PMOD connector, the signal you are seeing on the scope is to be expected. Remember, you will not see a sine wave, you will see one of 16 digital signals on your scope.  If you look at the signal with a faster time base, say 20nS/division, you should see a typical digital signal.  It may be somewhat distorted, since PMOD connectors are not very good for high speed signal integrity.  

If you want to see a sine wave, you need a digital-to-analog converter and connect your data bus to it.

15 Replies
600 Views
Registered: ‎06-21-2017

Can you post a picture of what you see on the scope?  Are your PMOD connectors digital outputs?   What voltage level?  how fast is your clock running? 

0 Kudos
Observer rica.soles
Observer
556 Views
Registered: ‎06-01-2018

Hi!

Thanks for answer.

This is my picture of oscilloscope.

osciloscopio.jpg

 

In my program the PMOD i configure from of Schematic. Look the picture. In this part i configure the port for PMOD JB and JC.

dds_3.jpg

 

This is my net list.

dds_4.jpg

 

Nexys video works with a clock the 100Mhz. I work with that clock for DDs.

 

0 Kudos
543 Views
Registered: ‎06-21-2017

While I am not familiar with the Nexis Video board, the description leads me to believe that the PMODs are not connected to a Digital to Analog converter.  If you have a 3.3V logic signal changing 100 million times a second going through a PMOD connector, the signal you are seeing on the scope is to be expected. Remember, you will not see a sine wave, you will see one of 16 digital signals on your scope.  If you look at the signal with a faster time base, say 20nS/division, you should see a typical digital signal.  It may be somewhat distorted, since PMOD connectors are not very good for high speed signal integrity.  

If you want to see a sine wave, you need a digital-to-analog converter and connect your data bus to it.

Observer rica.soles
Observer
526 Views
Registered: ‎06-01-2018

May be i dont explain well ... you have reason. I need to see each port . For example if my dds have 16 exits. I need to see any out in the oscilloscope, before connect any CAD. This for know if my DDS is working. But when i connect the oscilloscope in the PMOD a dont see nathing.
Furthermore, the pmod dont work for signals this type. You have reason.
Thanks for you help amd time.
Regards.

0 Kudos
Observer rica.soles
Observer
520 Views
Registered: ‎06-01-2018

But still I can not solve the problem. I already change ports and I still do not see anything. I adjust the oscilloscope to see some signal like those in the simulation and nothing.

0 Kudos
496 Views
Registered: ‎06-21-2017

From your siimulation, I think you are expecting a sine wave of 1MHz from your DDS.  What is the time base of your scope set to?  From your screenshot, it looks like it might be 500mS/division, but I don't know your scope.  This is way too long.  The Most significant Bit (MSB) of your DDS output should be a square wave of the frequency you are expecting.  Set your scope to something like 1uS/division and look at the MSB.  You could also put an ILA on the output of your DDS if you want to see what it is doing.

Observer rica.soles
Observer
478 Views
Registered: ‎06-01-2018

"The Most significant Bit (MSB) of your DDS output should be a square wave of the frequency you are expecting. "

Its correct, i do connect with the most significant bit and see the signal. In my case is the pin sen[15], and the DDS give me the frequency 1Mhz approx.

señal2.jpg

On the other hand, that signal not see well because the pin of nexys video not have a coupling system.

thank for your help and time.

0 Kudos
Observer rica.soles
Observer
468 Views
Registered: ‎06-01-2018

what is ILA?

0 Kudos
446 Views
Registered: ‎06-21-2017

The Integrated Logic Analyzer is a core that let's you monitor signals in the FPGA.  https://www.xilinx.com/support/documentation/ip_documentation/ila/v6_2/pg172-ila.pdf

Observer motagiyash
Observer
339 Views
Registered: ‎07-20-2018

Hey can you give us your testbench and guide lines like what you have done.

 

0 Kudos
Observer rica.soles
Observer
302 Views
Registered: ‎06-01-2018

Thanks for you help.

Regards.

0 Kudos
Observer rica.soles
Observer
301 Views
Registered: ‎06-01-2018

Hi!!!

What is the test breanch, is the same to simulation, you need images?

And other hand, you need the program in VHDL? I dont understan your question..."guide lines like what you have done." What do you meen?

Regards.

0 Kudos
Observer motagiyash
Observer
265 Views
Registered: ‎07-20-2018

Hello 

Plz help me out. I think i am missing somthing completly.

I just want to create the sine wave of 90 mhz.

i use sin cos lut mode.

i connected the clock and the constant.

whats the deal wit phase tdata .

i created a tb for wrapper.

But i get the wrong waveform.

entity tb is
--  Port ( );
end tb;


architecture Behavioral of tb is

component design_1_wrapper is
  port (
    m_axis_data_tdata : out STD_LOGIC_VECTOR ( 15 downto 0 );
    m_axis_data_tvalid : out STD_LOGIC;
    s_axis_phase_tdata : in STD_LOGIC_VECTOR ( 15 downto 0 )
  );
  end component;
 
 
 signal tdata       : STD_LOGIC_VECTOR ( 15 downto 0 );
 signal tvalid      : STD_LOGIC;
 signal phase_tdata : STD_LOGIC_VECTOR ( 15 downto 0 ) := x"0000";
  
begin

DUT : design_1_wrapper port map (m_axis_data_tdata=>tdata,m_axis_data_tvalid=>tvalid,s_axis_phase_tdata=>phase_tdata);

process
begin
 
phase_tdata <= phase_tdata + 1;

end process;

end Behavioral;

 

cccc.png
qsdf.png
0 Kudos
Scholar ronnywebers
Scholar
253 Views
Registered: ‎10-10-2014

your waveform looks strange, because you must tell Vivado's simulator/waveform viewer to interprete the values as signed or unsigned.

right-click on the 'strange' sine-waveform, and select the correct data-format

** kudo if the answer was helpful. Accept as solution if your question is answered **
Moderator
Moderator
240 Views
Registered: ‎08-16-2018
right click on the waveform-name in waveform viewer.
Next, click on radix and set it as 'signed decimal'.
It will show the expected waveform...