Altera cyclone V Technical Reference page 988

14-42
Power-On Reset Sequence
Figure 14-14: SD/MMC Controller Initialization Sequence
Power-On Reset Sequence
Software must perform the following steps after the power-on-reset:
1. Before enabling power to the card, confirm that the voltage setting to the voltage regulator is correct.
2. Enable power to the card by setting the power enable bit (
(
pwren
3. Set the interrupt masks by resetting the appropriate bits to 0 in the
4. Set the
Note: Altera recommends that you write 0xFFFFFFFF to the
interrupts before setting the
5. Discover the card stack according to the card type. For discovery, you must restrict the clock frequency
to 400 kHz in accordance with SD/MMC/CE-ATA standards. For more information, refer to
Enumerated Card Stack.
6. Set the clock source assignments. Set the card frequency using the
controller. For more information, refer to Clock Setup.
7. The following common registers and fields can be set during initialization process:
Altera Corporation
) to 1. Wait for the power ramp-up time before proceeding to the next step.
bit of the
int_enable ctrl
†
†
Assert Active-Low Reset
Enable Power to Card
Set Interrupt Masks
Enumerate Card Stack
Set the Clock Source Assignments
Set Other Controller Registers
power_enable)
†
register to 1.
†
bit to 1.
int_enable
†
in the power enable register
†
†
register.
intmask
register to clear any pending
rintsts
and
clkdiv clksrc
†
cv_5v4
2016.10.28
†
registers of the
SD/MMC Controller
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