inquiry on Artix7 board

[train04]

Dear sir,

i am shubham dwivedi , i have done a lot of work on  ARTY board  for implementing XADC ( 16 bit)   but i am not able to get correct output  (samples) , of my real time input waveform like SIN ,COS, TRIANGLE, RAMP signals ,  these i am giving by function generator . here also i am getting some kind of samples but it is not looking good .....when i have checked it with FFT (fourier transfourms) it is not recovering well......so i want to know is it possible to implement ADC on this board or another way is there to implement this,

i am using  1 Msps sampling frequency.

input signal i am giving less than 400 kHz.

please sir reply fast , i am struggling very much ....on this things. 

 

[hamster]

The XADC is a Dual 12-bit ADC. 1MS/s ADC. 

You are you getting the data off of the ARTY for analysis? Or are you using a Microblaze CPU?

Are you getting 1,000,000 reading per second? The ADCs are shared between multiple channels, so if you have 5 channels enabled you will at best only get 200k samples per channel.

It can also be set up as bipolar or unipolar mode - are you sure you have it configured right? can you show any of your configuration?

For unipolar signals the XADC's range is only from 0.0V to 1.0V - are you sure you are not driving it out of this range?

 

[D@n]

Hello @shubham dwivedi, and welcome to the forum!

You sound like you are on the right track, but let me offer you some pointers (it's all I can offer, since you haven't posted any code ...)

• Starting with a signal generator is perfect!  Keep that up, it's about as good of a test source as you will get
• Don't try debugging with the FFT until you know you are getting the right samples from the ADC
• Be careful with the clock issue--there's a trick or two involved in handling a 1MHz signal with a 100MHz clock. You'll want to make sure you are looking at only the right values
• Record samples from your device, and download them to your machine for graphical processing.  I prefer processing things with Octave.  Get away from a trace viewer as soon as you can--they just obscure the digital signal processing reality you are looking for (i.e., harder to see analog waveforms, harder to recognize analog waveforms in the middle of all the other surrounding logic, harder to visually separate the values of interest on every 100th clock from the other values, etc)
• If you haven't done so already, explore your results using a histogram.  In my experience, one common problem with ADC's is getting the bit ordering right.  A histogram will help you debug that.  Sine/cosine waves and square waves have very clear histogram signatures--use them.

Hope this helps!  Please write back and let us know how you are doing.  Sending code or traces from the component will also help us understand as well.

Dan

[train04]

hii hamster....

firstly thanks for reply ........

i am attaching some pictures which shows my configuration settings.

and i am using ARTY not the Microblaze CPU .............

please give some idea about it , if any mistake i am doing.

[D@n]

@shubham dwivedi,

Not using microblaze is a good start. 

I've never used the XADC wizard, so I'm not sure I can help you there ... I've always instantiated things directly via the library.  (p507)

Are you using Verilog or VHDL or other?

... and ... how do you know what output the XADC is giving you?  Are you certain that part of your design works?

Dan

[hamster]

11 hours ago, shubham dwivedi said:

hii hamster....

firstly thanks for reply ........

i am attaching some pictures which shows my configuration settings.

and i am using ARTY not the Microblaze CPU .............

please give some idea about it , if any mistake i am doing.

At a glance, from the last screen shot it seems you are sampling 10 channels, so that look to be about 100k samples per channel per second...

I haven't used the XADC that much at all. You would really need to have a a quick read of the user guide to find the bits of interest, then read them closely to find out exactly what you want to do.

Mike