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AM335x MMC High speed mode

takeshi matsuzaki
Expert 2030 points

Hello

Does AM335x MMC realy support High speed mode ?


1. AM335x read data from MMC

AM335x Data Sheet(SPRS717G)
P220 "Table 7-87"
Input Hold time is 3.76ns(min)

MMC Data Sheet(JESD84-A43)
Page 121 "Figure 56", Page 122 "Table 84"
Output hold time is 2.5(min)

So 3.76-2.5 = 1.26ns lacking for AM335x.

2. AM335x write to MMC

AM335x Data Sheet(SPRS717G)
P222 "Table 7-90"
Delay time is 2.5ns(min)

MMC Data Sheet(JESD84-A43)
Page 121 "Figure 56", Page 122 "Table 84"
Input hold time is 3(min)

So 3-2.5 = 0.5ns lacking for MMC.


AM335x can not operate MMC in High speed mode ?

Regards,
Takeshi Matsuzaki

  • 0
    TI__Guru**** 393215 points

    Hi Matsuzaki-san,

    Maximum MMC clock speed supported are listed in Table 18-3 from the AM335X TRM Rev. K. You can see that max. MMC clock frequency is 48MHz, therefore supported transfer speeds are:

    – up to 384Mbit/sec (48MByte/sec) in MMC mode 8-bit data transfer

    – up to 192Mbit/sec (24MByte/sec) in High-Speed SD mode 4-bit data transfer

    – up to 24Mbit/sec (3MByte/sec) in Default SD mode 1-bit data transfer

  • 0 in reply to Biser Gatchev-XID
    Expert 2030 points
    Hi Biser-san,

    Thank you for quick reply.

    I know the max. MMC clock frequency is 48MHz.
    I'm talking about setup and hold time.

    When AM335x read data from MMC, AM335x can not meet the MMC's hold time at min condition.
    When AM335x write to MMC, AM335x delay time can not meet the MMC's hold at min condition too,
    Even if operating at 48MHz, min condition could be occur, right?

    Regards,
    Takeshi Matsuzaki
  • 0 in reply to takeshi matsuzaki
    TI__Guru**** 393215 points

    Sorry, I don't have access to this JESD84-A43 datasheet you are referring, so cannot comment.