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Alex_V

PROBLEM WITH NEXYS A7 EVB

Question

Hi,

I am now working on the final project of the course.

During my work, I do a lot of tries where I change something in my code and download the Bit Stream into the chip via a standard USB JTAG procedure. It was working like this a lot of time, but unfortunately, it stopped working properly yesterday. 

 

Each time I am trying to download the Bit Stream all steps in Vivado are performed correctly but the board does not act as expected. Does not act as it acted before.

 

I tried different previously working codes and all of them do not work now! 

 

Also, I tried my codes on another similar board of my friend from the course and all the codes worked as before and as expected.

 

Very important to note that despite the written above the board DOES success to start and work with it's Demo Code that is stored in the Flash memory each time I power up the board. The Demo Code works like before.

 

Please advise what can be done.

 

Thank you,

Alex Vinitsky

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Hi @Alex_V,

Welcome to the Digilent forums!

Please elaborate on what is not working or the odd behavior.

Have you tried using different usb cables?

Is the mode jumper set to JTAG? 

What does the Nexys A7 show up as in the device manager under pots and universal serial bus controllers?

best regards,

Jon

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Hi Jon,

Have you tried using different usb cables? - YES

Is the mode jumper set to JTAG?  - see attached picture

What does the Nexys A7 show up as in the device manager under pots and universal serial bus controllers?

The board not only recognized by the PC it also connected to Vivado Hardware Manager - see attached picture

 

Thank you,

Alex

 

6c2a5094-d81b-4c67-857b-1bbe5a9afc81.jpg

af076442-8a5c-4d5a-baa6-6f88c77541ab.jpg

fa967888-7a3d-41cc-bedf-e938c4295011.jpg

ffffc36d-d1b3-4713-a3e3-9e5b7c1a51b4.jpg

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Hi @Alex_V,

In the attached picture the Mode Jumper is set to QSPI Flash.  JTAG Mode is the middle 2 pins.  I would suggest using the JTAG Mode to ensure there is no issues when configuring the FPGA.

Here is a screen shot of my windows device manager with a Digilent FPGA connected. I previously miss spelled the word ports as pots. You should see a com port for the FPGA as well as serial converter A and B when your Nexys A7 is connected to your PC and powered on as shown below.

image.thumb.png.d67545745f151c553e54143a1d2cead3.png

 

 

On 6/24/2019 at 12:17 AM, Alex_V said:

Each time I am trying to download the Bit Stream all steps in Vivado are performed correctly but the board does not act as expected. Does not act as it acted before.

What about the project is not working or acting differently? 

What type of project are you doing?

Have you tried powering the board through an external power source? 

Have you tried using your Nexys A7 on your friends PC?

best regards,

Jon

 

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Hi Jon,

I want to update you that I found the problem!

One of the push buttons (BTNc) became damaged and acted as a short in its open position.

Unfortunately, actually, this button was defined as global RESET in all my projects.

As a result, each time I was downloading the bitstream into the board the code was stuck on the RESET and never exit this state. That why nothing was working in all my projects.

That also describes why the Demo code was working as usual - the Demo does not use this particular button for RESET.

I remapped the RESET to another button and all my codes return working properly.

 

Thank you very much for your effort in trying to help me.

Best regards,

Alex Vinitsky

 

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Hi @Alex_V,

Glad to hear that you were able to find the issue and a work around. Thank you for sharing what the issue was and what you did.

best regards,

Jon

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