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Can't connect to JTAG when Microzed Connected to MBCC-IO Carrier

rdb9879

Greetings. When I have my Microzed (Z7MB-7Z0x0-PCB-F) disconnected from my carrier board (MBCC-IO-PCB-C), I can power the Microzed via micro-USB, the green "power good" LED illuminates, I can connect to the JTAG, and program the device using Xilinx Tools.

However, if I plug the same Microzed into the carrier board and power via the carrier board's 5V barrel connector, I can no longer connect to the JTAG (and I have tried both the JTAG connector on the Microzed as well as the JTAG connector on the carrier card itself). I get the message "No devices detected on target" even though the Xilinx JTAG USB module shows a green LED. I still see the green LED illuminated on the Microzed, but the "PWR GOOD" LED on the carrier card is not illuminated. I checked and confirmed that the Microzed's jumper settings are correct for "JTAG" mode, and that the jumper settings on the carrier card match the "defaults" in the user guide.

Using a multimeter, I measured the following voltages relative to ground:

TP1 = 3.298V

J3+ = 1.791V

TP6 = 0.0V

TP7 = 0.0V

TP8 = 0.0V

TP9 = 0.0V

TP10 = 3.295V

  • 0

    Hello rdb9879,

    When the SOM and Carrier Card are mated, you should only be able to access the JTAG inteface through the JTAG header on the Carrier Card. However seeing at the PWR_GOOD LED is not illuminated on the Carrier Card concerns me.

    How long have you had your SOM and Carrier Card?

    Are you sure your MicroZed is properly mated to your Carrier Card?

    Has the CarrierCard been modified from default configurations? (has an depopulated componented been added?)

    --Josh

  • 0 in reply to jafoste4

    I tried a different Microzed and the behavior was the same. 

    Both the SOM and Carrier Card are several years old, but essentially sat undisturbed in a cabinet until now. 

    I'm sure the MicroZed was properly mated. I applied even pressure to the 4 corners and checked for any tilting.

    If I read the user guide properly, I believe the jumpers are all in the default settings:

    CON3 = 1 shorted to 2 ("3V3")

    CON4 = 1 shorted to 2 ("3V3")

    J1 = 1 shorted to 2 ("PUDC#")

    The only electronic component that is not populated is U2, along with all its surrounding resistors and capacitors. There are several large capacitors not populated: C36, C35, C60, C61, C45, C46, C75, C67, C53, C20, C21, C22, C23, C24, C25, C2, C3, C4, C5

  • 0

    Hello,

    Based on the information your provided it seems that your Carrier Card may be damaged since multiple SOMs function properly withouth the Carrier Card however cannot function while attached.

    My suggestion would be to try and bring up the carrier card in standalone (no SOM present). To do so please refer to the hardware userguide. When you have it setup for standalone power up measure all the voltage rails to see if there are any issues present.

    --Josh

  • 0

    I looked in the MicroZed I/O Carrier Card Hardware User Guide Revision 1.3 (26 Aug 2014), but I can't find anything describing how to put the card in standalone mode. Can you help point me to the correct section?

  • 0

    Hello,

    Please refer to section 2.9. You will need to short J5 and J6. You will then be able to test the power supplies whithout the MicroZed inserted. This will require some soldering as these components are not fitted by default.

    --Josh

  • 0

    So I shorted J5 and J6, but I'm still not seeing the "PWR GOOD" LED. I used a multimeter to probe "PG_CARRIER", but it was only 0.10V. I'd normally just throw this board out and buy a new one, but it looks like Avnet is out of stock with an 8 week lead time, so I'm motivated to try and fix this board.

    Is there anything I should try measuring or replacing?

  • 0

    I think I found the problem: REG1 is damaged and is holding the PG_3V3 low. This is keeps REG3 and REG4 disabled, pulling PG_CARRIER low.

    I removed REG1 and now everything is working again, with the exception of getting the A1V8 signal (but I'm not using the DAC, so I can continue developing for now)