Korken

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  1. Like
    Korken got a reaction from Ahmed Alfadhel in Arty: I/O, max switching speed of the signals?   
    Hi again,
    I have received the board and have tested using the standard 200 ohm series resistors and 33 ohm replacements on a 100 MHz signal.
    What I did was simply to forward the input 100 MHz clock on the Arty to two output pins, one with the original series resistance on and one with my replacement.
    This was measured with an 16:1 passive (resistive) probe which presents itself as an load of about 800 ohms (made from an 750 resistor + coax), with a 50 ohm input termination on the scope (the image show 1Meg, this is from another channel).
    The results, as can be seen in the images, the 200 ohm pin still performs quite okey, though it was very sensitive to anything coming close or touching the board.
    The 33 ohm signal was rock solid. So I will continue and replace all the I/O resistors to 33 ohm, something a little bigger could probably be used as well but I have a lot of 33 ohm resistors.
    But is shows that the Arty has no problem, what so ever, with single ended signals up to 100 MHz so far.
    Another 2 cm of signal path will be added when I add my board, but this should not have any large effect on signal integrity at these speeds.
    Plus I have looked around the headers for GND points where I will solder extra GND paths, so there won't be a deficiency.
    @jpeyron Thanks for the signal lengths and the assistance!
     
    200 Ohm:

     
    33 Ohm:

     
    Probe:

  2. Like
    Korken reacted to jpeyron in Suggested update to Cmod A7 (v2)   
    Hi @Korken,
    Thank you for the suggestion on the Cmod A7. I have forwarded your SRAM suggestion to the appropriate people.
    cheers,
    Jon 
  3. Like
    Korken got a reaction from jpeyron in Arty: I/O, max switching speed of the signals?   
    Hi again,
    I have received the board and have tested using the standard 200 ohm series resistors and 33 ohm replacements on a 100 MHz signal.
    What I did was simply to forward the input 100 MHz clock on the Arty to two output pins, one with the original series resistance on and one with my replacement.
    This was measured with an 16:1 passive (resistive) probe which presents itself as an load of about 800 ohms (made from an 750 resistor + coax), with a 50 ohm input termination on the scope (the image show 1Meg, this is from another channel).
    The results, as can be seen in the images, the 200 ohm pin still performs quite okey, though it was very sensitive to anything coming close or touching the board.
    The 33 ohm signal was rock solid. So I will continue and replace all the I/O resistors to 33 ohm, something a little bigger could probably be used as well but I have a lot of 33 ohm resistors.
    But is shows that the Arty has no problem, what so ever, with single ended signals up to 100 MHz so far.
    Another 2 cm of signal path will be added when I add my board, but this should not have any large effect on signal integrity at these speeds.
    Plus I have looked around the headers for GND points where I will solder extra GND paths, so there won't be a deficiency.
    @jpeyron Thanks for the signal lengths and the assistance!
     
    200 Ohm:

     
    33 Ohm:

     
    Probe:

  4. Like
    Korken reacted to jpeyron in Arty: I/O, max switching speed of the signals?   
    Hi @Korken,
    I talked with our design and layout engineers. Unfortunately, we can not guarantee 72 Mhz but we think that the high speed and standard pmod ports will work for you.  Using either JB or JC Ports you should be able to get the fastest speeds off of those pins. Those traces are routed as differential pairs but you can use then as single ended. Noise might be an issue with JB and JC due to being routed as differential pairs so you will need to look out for that. Here is a thread that talks about using the high speed pmod ports. Also see section 10.2 High-Speed Pmod here.  The I/O resistors are accessible/replaceable on the bottom of the board and are labeled. You can use the schematic as a reference here. We do also have the Zedboard, Nexys Video and Genesys 2 that have a high speed FMC here which might be a better solution to your design needs. 
    cheers,
    Jon
  5. Like
    Korken got a reaction from JColvin in Zybo LVDS input to the High-Speed PMOD?   
    Thanks for the info!
    The 80 Ohms are a little difficult, I will have to add some impedance matching resistors but no problem.
    The camera has 115 Ohm out (due to a design decision) so two 18 Ohm resistors will be enough to get close to matched impedance.
    I will post some results as soon as I have them! 
  6. Like
    Korken got a reaction from endluri.ram in Upgraded Zybo Base System ?   
    Hi,
     
    I too have this problem, I was planning to use this in a course but the upgrade spits a lot of errors.
    Is there any upgraded version available Digilent?
     
    Thanks!
     
    Edit: I am running Vivado 2014.4.
     
    Best Regards
    Emil Fresk
    Luleå University of Technology
    Sweden
  7. Like
    Korken got a reaction from LariSan in Vivado Ip Axi Controller For Basys3 4 Digits Display   
    Nice work and really easy to use!
    I agree that some standard AXI IP templates would be nice, but you have started sooooo......
  8. Like
    Korken got a reaction from LariSan in Xdc Constraints Errors?   
    Okey, I made a last resort try.
    I changed the HDL wrapper for the block design to be VHDL (which I am more comfortable with), generated the bitstream and programmed the Zynq.
     
    And poof, everything is working!
    If I change back to the Verilog wrapper it stops working again. I could reproduce both on 100% new projects as well.
     
    Not sure what is making it go strange but I found a workaround.
  9. Like
    Korken reacted to elodg in Gigabit Ethernet   
    Could you point me to the exact example you are talking about? Also, posting specific questions rather than "manage the constraints" will increase your chances that someone will pick up your question. Is there an error you are getting, or perhaps a step you are stuck at?