Cyclone® V Hard Processor System Technical Reference Manual

ID 683126
Date 8/28/2023
Public
Document Table of Contents

A.4.4.1.1. Default Settings of the SD/MMC Controller

Table 273.  SD/MMC Controller Default Settings

Parameter

Default

Register Value

Card type

1 bit

The card type register (ctype) in the SD/MMC controller registers (sdmmc) = 0x0

Bus mode

SD/MMC71

Timeout

Maximum

The timeout register (tmout) = 0xFFFFFFFF

FIFO threshold RX watermark level

1

The RX watermark level field (rx_wmark) of the FIFO threshold watermark register (fifoth) = 0x1

Clock source

0

The clock source register (clksrc) = 0x0

Block size

512

The block size register (blksiz) = 0x200

Clock divider

Identification mode

32

The clock divider register (clkdiv)= 0x10 (2*16=32)

Data transfer mode

Bypass

The clock divider register (clkdiv)= 0x00

External Device Power enable Disabled (Power Off)

The power_enable bit in the pwren register is programmed to 0x0 out of reset, meaning the sdmmc_pwren signal is not active and does not do anything at boot time. A pull-up should be attached to the sdmmc_pwren pin for proper functionality.

Note: If the SD/MMC controller is used as the boot source, then power to the corresponding SD card must be supplied from a power controller on the board. After boot has completed and the SD/MMC controller has been fully configured, the sdmmc_pwren signal can be used to turn on and off the SD card through the pwren register.
71 SPI cards are not supported for boot.