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TPS65950 VMMC1 driven for Boot ROM MMC boot?

Pev
Prodigy 245 points
Other Parts Discussed in Thread: OMAP3503, TPS65950

Hi all,

  I'm having a bit of a braindead moment. We have a design based on the OMAP3503 and TPS65950. We wish to MMC boot (via the boot ROM) and have SYS_BOOT pins on the OMAP as follows :

  • SYS_BOOT0 : H
  • SYS_BOOT1 : H
  • SYS_BOOT2 : H
  • SYS_BOOT3 : H
  • SYS_BOOT4 : L
  • SYS_BOOT5 : H
  • SYS_BOOT6 : H 

From the OMAP35x TRM I understand that this means we should be doing a peripheral boot :

  USB -> UART3 -> MMC1 -> OneNAND

However this is all governed by the Boot ROM in the OMAP. I don't understand in this scenario how the TPS65950 knows to power up the VMMC1 supply for the card to make this happen. It obviously can, as on the Mistral EVM this occurs correctly and works, but in our design it fails.

Can anyone enlighten me as this has me scratching my head in much confusion!

Best Wishes,

~Pev

 

  • 0
    TI__Genius 15100 points

    Hi,

    Here is the response from OMAP support -

    Yes, the ROM sends i2c commands to turn on the voltage.   They should see 3V on VMMC1 when MMC1 is in the boot sequence.

    Hope this helps.

     

    Regards,

    Gandhar.

     

  • 0 in reply to Gandhar Dighe
    Prodigy 230 points

    HI , Gandhar

     

       What's the impact of card detect function? How the CD1 was used ? The datasheet said it would trigger a interrupt to turn on VMMC1 LDO，while the OMAP processor would issue a "turn on" command also. The datasheet also mentioned the card extract would turn off the LDO .   what's the priority?  

     

    Thanks a lot !