Description
Direction
Clock Name
Phase-shifted clock of
sdmmc_clk_divided
used to sample the command and data from the
card
Internal
sdmmc_sample_clk
Phase-shifted clock of
sdmmc_clk_divided
for controller to drive command and data to the
card to meet hold time requirements
Internal
sdmmc_drv_clk
Figure 11-10: SD/MMC Controller Clock Connections
Divide
by 4
Phase
Shifter
Phase
Shifter
sdmmc_cclk_out
l4_mp_clk
sdmmc_clk
sdmmc_clk_divided
sdmmc_drv_clk
sdmmc_sample_clk
SD/MMC
Controller
Core
The
sdmmc_clk
clock from the clock manager is divided by four and becomes the
sdmmc_clk_divided
clock before passing to the phase shifters and the SD/MMC controller CIU. The phase shifters are used to
generate the
sdmmc_drv_clk
and
sdmmc_sample_clk
clocks. These phase shifters provide up to
eight phases shift which include 0, 45, 90, 135, 180, 225, 270, and 315 degrees. The
sdmmc_sample_clk
clock can be driven by the output from the phase shifter.
The selections of phase shift degree and
sdmmc_sample_clk
source are done in the system
manager. For information about setting the phase shift and selecting the source of the
sdmmc_sample_clk
clock, refer to the
Clock Setup
section within this document.
Note:
The controller generates the
sdmmc_cclk_out
clock, which is driven to the card. For more information
about the generation of the
sdmmc_cclk_out
clock, refer to the
Clock Control Block
section within this
document.
Related Information
•
Refer to this section for information about setting the phase shift.
•
on page 11-25
Refer to this section for information about the generation of the
sdmmc_cclk_out
clock.
SD/MMC Controller
Altera Corporation
cv_54011
Clocks
11-28
2013.12.30