Zybo Ethernet has variable time to turn on Ethernet

[zerosmx]

On a design with the Ethernet hardware connected, I have a program loaded from the Xilinx SDK echo server example.

 

Sometimes this program works fine.

 

But sometimes I can't get any connection to the board.

 

On the board itself, I can see whether or not the connection will work because the "LINK" LED is not lit up whenever the failure occurs.

 

However, I can't figure out why sometimes I turn on the board and the Link comes up within a few seconds, and other times it never seems to come on at all.

 

Sometimes I can see the ACT light flashing, sometimes I can't.

 

All I am doing in between attempts is pushing the PS-SRST button, so nothing is changing in between attempts with the hardware on either side.

 

Has anyone else seen this kind of behavior?

[jpeyron]

Hi @zerosmx,

1) What do you have connected to the Zybo while you are pushing the PS-SRST?

2) How are you powering the Zybo?

3) Does this happen when you turn off the Zybo and turn it back on , program the FPGA and then run the Application?

thank you,

Jon

[zerosmx]

Hello,

 

1. The setup is the Zybo, running from an SD card. Connected is a UART which I am monitoring through PuTTy. Putty shows normal text that should be displayed from the Echo Server test. Also connected is an Ethernet cable which is in this case directly connected to the host computer, which is configured with a static IP address. No other hardware is involved.

2. The Zybo was powered from UART. I have just tested the device by switching to wall power, and see the same behavior.

3. When I program the FPGA and .elf through the SDK interface, I am still not seeing the link come up, although I am seeing the ACT light blink periodically. If I pause the debugger it shows that the code has  proceeded to the main loop, which means that it already passed the network interface initialization stage. I also attempted to write my code to QSPI and run from there, to similar effect.

[jpeyron]

Hi @zerosmx,

1) To confirm the situation, every time you press PS-SRST on the Zybo the Zybo is being configured and the DONE led is coming on but the Ethernet link is not being established every time. Is this correct?

2) Are you using something like wireshark to better see the back and forth Ethernet communication between the PC and the Zybo? If so what are you seeing? If not please download wireshark and see what is going on between the PC and the Zybo.

3) Is there a difference in communication with the times that the Ethernet link is establish and when the Ethernet link is not established?

thank you,

Jon

 

[zerosmx]

@jpeyron

1. Correct, when I press the reset button, LD12, "DONE", lights up afterwards. At this point I can see LD8, "ACT" blink sporadically, but LD7, "LINK" does not light up. Sometimes it will never seem to light up, sometimes LINK will come up after a few seconds.

2. I have downloaded wireshark, but I'm not familiar enough with networking to know what any of this means. I have attached the capture. In this case I started a wireshark capture, then turned on the board. After a while, I pressed the PS-SRST. At no point did the LINK come up during this time.

3. I can't really tell. From the application side, the difference is that when LINK is not up the board doesn't seem to respond to any attempts to communicate with it and the attempt times out. When LINK is up the echo works fine.

wireshark.pcapng

[jpeyron]

Hi @zerosmx,

1) What version of Vivado/SDK are you using?  

2) Are you following this older Getting Started with Zynq Servers tutorial? 

3) Did you alter the echo.c? 

thank you,

Jon

 

[zerosmx]

@jpeyron

 

1. Xilinx 2018.1

2. I checked through that guide, and I've followed all the steps described there.

3. No, I made a new project with the base echo.c to test this. The only difference is that I enabled debug info in the FSBL

[jpeyron]

Hi @zerosmx,

Do you see the same issues when configuring the Zybo from SDK and not using a FSBL with  either the FLASH or the  SD?

thank you,

Jon

[zerosmx]

@jpeyron

 

If I go through SDK and program flash and then debug through SDK, then I still do not see LINK come up.

[jpeyron]

Hi @zerosmx,

1)  Are you compressing the bitstream? 

2) Try adding a delay to the FSBL.

3) Are you able to get  a standard none FLASH Ethernet project working on the Zybo from SDK?

thank you,

Jon

[zerosmx]

@jpeyron

 

1. I don't think I am compressing anything, at least I am not doing so explicitly. It's possible the "Create Boot Image" utility does that? But I personally am not.

 

2. How would I go about adding such a delay?

 

3. Programming through JTAG and running on RAM produces the same results as running from FLASH

[jpeyron]

Hi @zerosmx,

1) Are you following the  Getting Started with Zynq Servers tutorial for making the non QSPI/SD project? If not please use this tutorial to verify your ethernet. 

2) Have you tried using a different PC and Ethernet cable?

thank you,

Jon