Manual DLL Programming Sequence

Versal ACAP Technical Reference Manual (AM011)

Document ID
AM011
Release Date
2022-04-26
Revision
1.4 English

Program the DLL by writing to these registers in the SD_EMMC register module.

  1. Disable SD clock by writing 0 to the CLK_CTRL [SDClkEn, 2] bit.
  2. Select the TX tap by writing to the OTAP_DLY [sel] bit field.
  3. Program new input tap value using the ITAP_DLY register.
    1. Disable clock output. Write 1 to the [change_window] bit.
    2. Write new input tap value. Write 1 to [dly_en] and tap value to [sel].
    3. Enable clock output. Write 0 to the [change_window] bit.
  4. Wait for the SD clock to stabilize. Read CLK_CTRL [IntClkStable] bit until it is = 1.
  5. Enable the SD clock. Write 1 to [SDClkEn].