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microzed sbc I don't see anything in the boot  througth serial port or usb

Former Member
I was expecting to see the kernel messages when i booted my microzed sdb but the USB isn't detected by my computer and when i tried the connect the uart that is in the J3 connector it seems that the embeded linux don't detect this serial port. 
I write the default sd that is in microzed webpage and I know that microzed is working because I can access it throught IP (192.168.1.10) but i can't see anything throught serial port.  In /proc/tty/driver/ it seems that only one uart is recognized ttyPS0 but i guess that two uarts have to be recognized by linux because two uarts are implemented in hardware.
How can i see the kernel messages on the serial port when microzed starts?
  • 0

    Hi Jose,

    Have you downloaded and installed the Silicon Labs CP210x USB to UART?

    http://zedboard.org/support/documentation/1519

    --Josh

  • 0 in reply to jafoste4

    Yes, I installed it. I read that the usb in this microzed is configured as host in default configuration, may be this is the reason i don't detect any device when i plug it.  But  I need a solution to see the kernel messages throught serial port. any ideas?

  • 0

    Hi Jose,

    According to section 2.3.2 of the MicroZed SBC Hardware User Guide, you will need an external USB-UART adapter to plug into the Pmod header as that is where the serial terminal UART is routed to:

    http://picozed.org/sites/default/files/documentations/MicroZed_SBC_HW_UG_v2_1.pdf

    According to section 2.3.2:

    "UART (Digilent Pmodu2122 Compatible Header)
    MicroZed has one Digilent Pmodu2122 compatible header (1x6). This is a right-angle, 0.1u201D male
    header that includes four user I/O plus 3.3V and ground signals. MicroZed SBC implements a
    UART interface connected to a PS UART peripheral via this header. Utilizing a Digilent
    PmodUSBUART device allows connection to a host computer. Only basic TXD/RXD connection
    is implemented.
    The uart1 Zynq PS peripheral is accessed through MIO[48:49] in MIO Bank 1/501 (1.8V). The
    1.8V UART signals are translated to 3.3V via a TI TXS0102DQE device. The Digilent
    PmodUSBUART features adjustable I/O voltage, so it is connected directly to Zynq providing the
    jumper on the Digilent device is set properly to 3.3V.
    This connector also contains two GPIO pins connected to the Zynq PS bringing the total available
    PS signals to four that are wired to this header. If UART communication via this port is not
    necessary, these four pins are capable of being used as general purpose interfaces in the 1x6
    Pmod configurations. In this scenario, UART type functionality would have to be created by one
    of the other peripheral communications interfaces. This is a non-standard option."

    Regards,

    -Kevin

  • 0 in reply to zedhed

    You are right this is what i meant when i talk about J3 connector serial port. I tried to connect a serial port there and I can't see nothing when the microzed is powered on. I even flip the connectors RX-TX to be sure that all possible connections are tested but there is no answer from the microzed. I don't know what to change to see the kernel messages through serial port....

    Thanks in advance for your replies...

  • 0 in reply to Former Member
    Now the SD contains the files from "MicroZed Linux microSD Card Image Archive" downloaded from microzed support page. The microzed is working and I can see nothing trougth J3 uart, but i can connect using telnet.
    when I use a multimeter to check voltages in this serial port I find that there is -3.3v in RX (J3-2 pin) and 0v in TX (J3-3 pin). As far as i know this is not the common way of working of a serial port. Usually every device set 3.3v volts in its TX pin.  Are we sure that behind these pins there is a uart or may be that in this ocassion this pin is set as a general purpose pin?. I don't understand negative voltages in the uart. Usually usb-to-uart converters use 0v to 3.3v voltages.
    any suggestions?
     
  • 0

    Hi Jose,

    Pins 48/49 are used for (UART1) - just like the MicroZed. If Linux is not showing on the terminal, then you most likely are not setting up UART1 properly in Linux or are not hooking up the PMOD UART correctly. The PMOD makes this interface look just like the standard MicroZed. Please double check the UART PMOD and Linux Configurations and report back.

    Thanks,

    Josh

  • 0 in reply to jafoste4

    Hi Josh

    I'm using the linux version that is supplied by xilinx in it's web page "http://microzed.org/product/microzed". They supplied a SD image:  "MicroZed Linux microSD Card Image Archive". I know that this image works because I can connect to microzed by TCP.  I don't know how are configured the uarts in this software but i guess that I can see the linux startup through serial port.

    On the other hand, the port connections are quite simple and only three wires are needed. GND, RX, TX.
    I tested the two connection posibilities. Cross cable and straight cable.

    * First option (cross cable):
    RX microzed     (J3-2 pin)  <->  TX 3.3v usb converter.

    TX microzed (J3-3 pin)  <->  RX 3.3v usb converter.

    GND microzed (J3-5 pin) <-> GND usb converter

    * Second option (straight cable):
    RX microzed     (J3-2 pin)  <-> RX 3.3v usb converter.

    TX microzed (J3-3 pin)  <->  TX 3.3v usb converter.

    GND microzed (J3-5 pin) <-> GND usb converter

    As you can see I tested all posibilities but I can't see the linux terminal. 
    I don't know why it doesn't work. How can i test if all is correctly configured in this linux version ?,
    What is the dev in linux for this uart?.
    Is this uart an standard 3.3v port? 

     
  • 0

    Hi Jose,

    I am looking at the MicroZed SBC Hardware User Guide here:

    http://microzed.org/sites/default/files/documentations/MicroZed_SBC_HW_UG_v2_1.pdf

    Also at the MicroZed SBC Schematics here:

    http://microzed.org/sites/default/files/documentations/MicroZed_SBC_B_SCH_05072014.PDF

    I do not see any UART lines on J3 indicated in those documents, did you mean J4 instead?

    We connected a stock SBC here in the lab, set the mode jumpers to SD Card boot mode, and booted into a PetaLinux 2014.4 design.

    http://microzed.org/support/design/1519/10

    We are able to observe console output using one of these Digilent Pmod devices plugged into J4:

    http://store.digilentinc.com/pmod-usbuart-usb-to-uart-interface/

    Can you please confirm that you are connected to the right header for UART?

    Regards,

    -Kevin