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Breakout Carrier Card I/O Voltage Levels

Former Member

I am using the Microzed Breakout Carrier Card (BCC) to prototype some hardware control circuits and I need 3.3V control signals.

I am trying to set my bank 34 and 35 voltages to 3.3V. Bank 35 seems ok, but I cannot get my bank 34 voltage to go beyond 1.8V. I have checked that VCCIO is indeed 3.3V on both banks 34 and 35.

Everything in Vivado seem to indicate that the I/O STD is set to LVCMOS33.

My BCC jumper is set to 3.3V.

In my constraints file I am using

set_property IOSTANDARD LVCMOS33 [get_ports -of_objects [get_iobanks 34]];

set_property IOSTANDARD LVCMOS33 [get_ports -of_objects [get_iobanks 35]];

Any ideas? Thanks.

  • 0

    You do need to make sure that the set_property IOSTANDARD LVCMOS33 [get_ports -of_objects [get_iobanks 35]];   statement is after any Bank 35 I/O pin constraint in the .xdc file.

     

    Here is the note from the master constraints file:

    # IOSTANDARD Constraints
    #
    # Note that these IOSTANDARD constraints are applied to all IOs currently
    # assigned within an I/O bank.  If these IOSTANDARD constraints are 
    # evaluated prior to other PACKAGE_PIN constraints being applied, then 
    # the IOSTANDARD specified will likely not be applied properly to those 
    # pins.  Therefore, bank wide IOSTANDARD constraints should be placed 
    # within the XDC file in a location that is evaluated AFTER all 
    # PACKAGE_PIN constraints within the target bank have been evaluated.

     

    -Gary

  • 0

    Thanks Gary for your quick response.

    My two calls to set_property are at the end of the constraints file.

    Is it possible that something is not being reset in Vivado? I am using Vivado 2015.2.

    I tried swapping the order of the set_property call but still the same results.

  • 0

    Are you measuring 1.8V on VCCO_34? While VCCO_35 is 3.3V? That would be very odd since both are tied together on the Breakout Carrier. If so, please let us know exactly where you are taking the measurements.

     

    The MicroZed itself has additional regulation for the PS MIO Banks, with Bank 0 fixed at 3.3V and Bank 1 fixed at 1.8V.

     

    Bryan

  • 0

    On the MZ BCC

    VCCO (CONN1 PIN 53, 54) = 3.3V
    VCCO (CONN2 PIN 49, 50) = 3.3V

    I can write CONN2 PIN 37 = 3.3V

    When I write CONN1 Pin 10-17, 19-22 = 1.8V.

    I'm going to try swapping some pins to different banks to see what happens. I will let you know if I find anything.

  • 0

    As another note I'm not doing anything special to change the bank voltage levels other than set the jumper to 3.3V and set the LVCMOS33 property.

    Do I need to do anything with the PG_CARRIER pin or any other special pins on the breakout carrier card? Right now I'm not driving those pins at all.

  • 0

    Can you confirm that you have JP2 set to 1-2? You do not need to do anything with PG_CARRIER.

     

    What is the code that you are using to drive 3.3V on the CONN1 I/Os?

     

    Bryan

  • 0

    Thanks for all your help. It turns out the code I was running was driving the pin high, then low, very quickly. (It should have been just driving it high.) When I read this output voltage on a multi-meter it read 1.8V - which happened to be another possible signal level of the card - which is what lead me to suspect I was not doing something right with the card.

    I fixed the code and now I am successfully getting 3.3V out on both CON1 and CON2. All I had to do to configure the card was set the jumper to the desired voltage level and set my constraints file to match that level.

    Thanks again!