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AM5728: Board booting issue

ROSHAN RAJAGOPAL
Intellectual 315 points
Part Number: AM5728

Tool/software:

Hi,
I am booting an custom am5728 board,i am facing problem as shown below where i feel the u boot isn't switching from 1 bit mode to 4 bit mode.

U-Boot SPL 2018.01-00569-gfd38f5afef-dirty (Sep 25 2024 - 12:30:26)
DRA752-GP ES2.0
Trying to boot from MMC1
no pinctrl state for default mode
no pinctrl state for default mode
omap_hsmmc_send_cmd: timedout waiting on cmd inhibit to clear
omap_hsmmc_send_cmd: timedout waiting on cmd inhibit to clear
omap_hsmmc_send_cmd: timedout waiting on cmd inhibit to clear
unable to select a mode
spl: mmc init failed with error: -524
SPL: failed to boot from all boot devices
### ERROR ### Please RESET the board ###

since we don't reach the point of u-boot prompt also we don't know what to do.

The questions i have regarding this is as below:

  1. Could you let me know the booting communication between the processor and the SD card that takes place , step by step for example how it changes from 1-bit to 4-bit mode and is the ram involved in between this. A flow chart showing the communication of boot process between the processor and SD card to fully boot the board would help.
  2. This is not a software problem as other boards boot with the same SD card and only few boards face this issue. Could you give an idea on where to check in the hardware section to solve this issue.

    I have checked all these resistors and the clock signal and cmd signal which show a pulse in the starting, also dat0 line shows a pulse as soon as we power on the board.
    Could you help me check anything else in the hardware section that might be involved and might be faulty at the moment.

    Also please note that we do not have access to Jtag

    Regards ,
    Roshan Rajagopal
  • 0
    TI__Mastermind 31634 points

    Hello Roshan,

    Your thread has been assigned to the mmc HW engineer. Please see initialization chapter of the TRM for basic booting procedure as well as details of mmc environment and integration. Chapters 33 and 25 respectively.

    -Josue

  • 0 in reply to Josue Zamitiz-Ayala
    Intellectual 315 points

    Hi,
    Thank you josue , we will be waiting for your reply while we check the booting procedure.

    Regards,
    Roshan Rajagopal

  • 0 in reply to ROSHAN RAJAGOPAL
    Intellectual 315 points

    Hey,
    As of yesterday there is a board where when powered on all the voltages come properly , there is a signal transmission on the cmd and data0 and clk line, but nothing shows up on the minicom screen.
    Is there any update on what i should check on the hardware side?

    Regards,
    Roshan Rajagopal

  • 0 in reply to ROSHAN RAJAGOPAL
    TI__Expert 3080 points

    Hi Roshan,

    ROSHAN RAJAGOPAL said:
    I am booting an custom am5728 board,i am facing problem as shown below where i feel the u boot isn't switching from 1 bit mode to 4 bit mode.

    Can you share schematic layout for the custom board to help debugging?

    Best Regards,

    Matt

  • 0 in reply to Matt Park
    Intellectual 315 points

    Hi,
    The schematic is fine and follows the same as the evm board for PMIC , SD card and DDR section.As i had mentioned only some boards i face this issue and i am confused on where to see for debugging.

  • 0 in reply to ROSHAN RAJAGOPAL
    TI__Expert 3080 points

    Hi Roshan,

    Additionally, please provide information on these things:

    • What is the SD card size and type you are using?
    • What speed mode are you using when trying to boot?
    • Do the boards you that have problems always show this issue?
      • If not, how many times on average out of 10?
    ROSHAN RAJAGOPAL said:
    As of yesterday there is a board where when powered on all the voltages come properly , there is a signal transmission on the cmd and data0 and clk line, but nothing shows up on the minicom screen.
    • Are you changing anything in between booting?
    • Have you tried switching out a new SD to see if one has been corrupted?
    • Have you tried re-flashing a new SD card?

    Best Regards,

    Matt

  • 0 in reply to Matt Park
    TI__Guru 52065 points

    When interfaces work on some boards but not others - can sometimes indicate a design parameter (voltage level, timing margin, etc) is marginal.  Have you checked to make sure both high and low IO levels are correct.  When Uboot switching from 1b to 4b mode, is speed also changing?  Does slowing down the interface help?  Could be a timing parameter is not being met.  The PCB implementation can impact signal quality - if it is creating reflections.

    Manufacturing errors can also cause some boards to work, others to not work properly.

  • 0 in reply to Matt Park
    Intellectual 315 points

    Hi,
    we did try these and it did not solve the issue , we traced the issue on the cmd line and data 3 line which were shorted and caused the issue of the error to come.
    but we are still not able to trace where the problem is for the board where nothing comes up as there is no short on the data and cmd lines.
    Should we check the RAM termination resistors , does it get involved before the  uboot loads??
    If not could you let us know from where can we start the checks?

    Regards,
    Roshan Rajagopal

  • +1 in reply to ROSHAN RAJAGOPAL
    TI__Guru 52065 points

    If I understand correctly - one board that was failing was due to manufacturing issue.  It is possible the other board is also a manufacturing issue also, maybe just a different issue.  Opens are also possible (no solder connection)