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boot from emmc0 with 4GB

Eliah Ninyo
Intellectual 820 points
Other Parts Discussed in Thread: AM3359

hello,

I preparing aboard based on the AM3359 SItara processor.

I read here (https://e2e.ti.com/support/arm/sitara_arm/f/791/t/244650) that in Sep 2014 is it not recommended to boot from mmc0.

I still don't understand it. the restriction from TRM 26.1.7.5.2 says "the  restriction is  a reslut of many eMMC devices not being compliant with the eMMC v4.41 specification". so if I have a device compliant with eMMC v4.41 (actually 4.5) is it ok?

using MMC1 is less good for me since table 26-7 (SYSBOOT) have MMC1 only in one place. and I need the UART0 option to be before the MMC option - and there is not option for that with MMC1.

any suggestion? is there any change since Sep 2014?

 

P.S.

Beaglebone board uses this 4GB flash but on MMC1...

  • 0
    TI__Guru**** 393215 points

    Hi Eliah,

    I recommend you test this beforehand on one of the AM335X EVMs with an adapter PCB with your eMMC on it, plugged in the SD card slot. There are simply too many devices on the market for the factory team to be able to cover all of them. Another approach that may help is try to choose a couple of SYSBOOT combinations that can be selected by a DIP switch - like on the Beaglebone Black.

  • 0 in reply to Biser Gatchev-XID
    Intellectual 820 points
    Hi,
    thanks for the quick answer.
    I don't have a PCB adapter for the flash I want to use (I would like to use the same 4GB flash like in the beaglebone board).

    I don't understand your other approach - sysboot can not be change during boot. in the EVM we have DIP switch, but in my board I want to pick static one. since there is no one with UART0 before MMC1, i'm asking if there can be some flexability with the reserved state or something like that? (to make a new sequence as I desire).

    regards,
    Eliah
  • 0 in reply to Eliah Ninyo
    TI__Guru**** 393215 points

    Can you describe why do you need UART before MMC? There is no way to change the boot sequence except by SYSBOOT pins.

  • 0 in reply to Biser Gatchev-XID
    Intellectual 820 points
    I need the UART before MMC because if for some reason the boot from MMC succeed but the application is crushed on the start (or even the boot crushed at the end of it) then i'm stuck.
    I want the ability to wake up from UART for those cases...

    SYSBOOT pins as fat as table 26-7, doesn't support MMC1 after UART0 (MMC0 does have such option)
  • 0 in reply to Eliah Ninyo
    TI__Guru**** 393215 points

    Eliah,

    I requested another opinion on this. Feedback will be posted here.

  • 0 in reply to Biser Gatchev-XID
    TI__Guru* 86180 points

    Eliah, you should be able to get the adapter from Micron to test the device.  Once again, if it is compatible with v4.41, it should work but it would be best to test it out beforehand.  Even though there is no UART before MMC1 in the SYSBOOT sequence, what was done on beaglebone is a small pushbutton which changes one of the SYSBOOT signals.  Pushing this down while powering up the board changes the boot sequence.  If you can accommodate this on your board, that would be one workaround to choose a different boot sequence to enable UART boot in case of a crash.

    Regards,

    James