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Zedboard system reset button

Former Member

Hi: I just bought a Zedboard and I am following the Getting Started instructions of loading a simple linux image from the SD card.

Everything works as described, but I cannot find an external board reset button. I see two red-colored buttons named PS-RST and PROG. When I pressed the PS-RST button (which resets the ARM), the COM port displayed an autoboot message, and the ARM tried to reload the linux image from the SD card. However, it always stopped at xgpiops. I then tried to press both PROG and PS-RST buttons, but the outcome remained the same (linux boot stuck at xgpiops).

Based on the HW User Guide, the power-on reset signal is called PS_POR_B, but this signal is not connected to any push button. Does this mean the Zedboard can only be reset by toggling the power switch?

Thanks!

  • 0

    As you have gleaned from the HW Users Guide there is a hierarchy of resets. The PS_POR_B reset is driven directly by the board's power hardware and the reset functions controlled by this signal can only triggered by toggling power to the board. So things like reading the Boot Configuration Mode pins, the SoC Debug Domain, and some of the internal Registers are only reset by this signal.

     

    The PS_RST button is tied to the Zynq PS_SRST_B input signal and pushing this button will generate Zynq peripheral resets, configuration resgisters, etc. This Zynq reset hierarchy is documented in the Zynq TRM (UG585) in Chapter 26. Here is a reset block diagram from UG585:

    image

     

    -Gary

  • 0 in reply to Former Member

    Dear Gary:

    Thank you very much for the prompt response. I have downloaded UG585 and will peruse it later. Can you tell me why typing the command "reboot" in the linux shell does not work? I get the message "Reboot failed -- System halted". It seems bad to me that the Zynq cannot truly emulate a linux machine. The PS-RST reset button also cannot be used to reboot linux. Only toggling the power switch works.

    Thanks!

  • 0 in reply to Former Member

    The PS_RST reset button can normally be used to reboot Linux. The image on the SD Card was generated using an earlier version of the Xilinx tools that had a bug in the FSBL generation. If you download a current version of Linux for the ZedBoard from the Xilinx website http://www.wiki.xilinx.com/Zynq+2013.4+Release the reset button will reboot Linux. Likewise the reboot command will work with the newer Linux boot. The issue is not with the ZedBoard.

     

    -Gary