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AM3517: RBL related speed optimizations?

Wolfgang Denk
Prodigy 35 points
Other Parts Discussed in Thread: AM3517, OMAP3530

It appears the RBL in the AM3517 takes a pretty long time before it loads and starts any code from NAND;

the same operation on a OMAP3530 (say, on a beagleboard) is significantly faster.

Is there anything that can be done either in the hardware design and/or in the software configuration to

make the RBL boot as fast as possible?

Thanks in advance,

Wolfgang Denk

  • 0
    TI__Intellectual 1250 points

    The boot sequence of both devices is determined by the external SYSBOOT pins.  On beagleboard, these pins are hardwired and the sequence starts with NAND followed by USB, UART then SD card.  It is also possible to use the User/Boot button to change this sequence to that NAND is last.

    If the SYSBOOT pins are set the same on the AM3517 hardware (NAND first), then the two boot times should be similar.  On the AM3517 EVM, the SYSBOOT pins are accessible and can be set to be the same as Beagleboard.  You didn't mention the hardware that you are using for AM3517.

    Greg

  • 0 in reply to gkturner
    TI__Intellectual 1250 points

    On the TAM-3517 module, it looks like the SYSBOOT pins are set up the same as beagleboard except for SYSBOOT5 which is set to 1.  This means that the device will go through a "Peripheral preferred" boot sequence USB, UART, SD, NAND.  Beagleboard has SYSBOOT5 set to 0.  This is "Memory preferred" booting which goes NAND, USB, UART, SD.

    Greg

  • 0 in reply to gkturner
    Prodigy 40 points

    WARNING: this will void you warranty / support etc /WARNING

    On the tam3517 the sysboot5 is determined by a resistor on the TAM3517 board.
    Your not advises to alter it.

    If you insist: with the connector down, there is a series of 5 resistors above 7 resistors and a capacitor above the chip.
    (in the AE/1 corner). For rev A and B these are mounted, mounted, not mounted, mounted, mounted.

    Removed the left resistor, and sysboot5 will be zero.

    Note: make absolute sure there is something valid in NAND or it will be bricked (or above resistor needs to be shorted at boot)
    Note2: according to the specification it needs a pull down, it is likely floating like this.
    note3: again, you do this at your own risk

  • 0 in reply to Jeroen Hofstee
    Prodigy 20 points

    Could you describe the dispositions of all other SYS_BOOT[0..5] resistors?

    Thank you very much!

  • 0 in reply to Anton Ivanov1
    Prodigy 40 points

    I am unable to tell you which resistors control the other sysboot configuration, since I don't have the schematics. You can better ask Technexion.

    The mentioned adjustment is found by trial and error. According to Technexion, the proper way to do that is by swapping r13 and r14.

  • 0 in reply to Jeroen Hofstee
    Prodigy 20 points

    You are right, SYS_BOOT5:

    R14 - is pullup

    R13 - is pulldown

    I also found that the permutation resistor R19 to position R20 switches SYS_BOOT4.

    R20 - is pullup

    R19 - is pulldown

    Investigations continue :-)