• The response timeout field (
response_timeout
) of the
tmout
register. A typical value is 0x64.
†
• The data timeout field (
data_timeout
) of the
tmout
register, highest of the following:
†
• 10 * N
AC
†
N
AC
= card device total access time
†
= 10 * ((TAAC * F
OP
) + (100 * NSAC))
†
where:
†
TAAC = Time-dependent factor of the data access time
†
F
OP
= The card clock frequency used for the card operation
†
NSAC = Worst-case clock rate-dependent factor of the data access time
†
• Host FIFO buffer latency
†
On read: Time elapsed before host starts reading from a full FIFO buffer
†
On write: Time elapsed before host starts writing to an empty FIFO buffer
†
• Debounce counter register (
debnce
). A typical debounce value is 25 ms.
†
• TX watermark field (
tx_wmark
) of the FIFO threshold watermark register (
fifoth
). Typically,
the threshold value is set to 512, which is half the FIFO buffer depth.
†
• RX watermark field (
rx_wmark
) of the
fifoth r
egister. Typically, the threshold value is set to
511.
†
These registers do not need to be changed with every SD/MMC/CE-ATA command. Set them to a typical
value according to the SD/MMC/CE-ATA specifications.
Related Information
•
on page 11-34
Refer to this section for information on setting the clock source assignments.
•
on page 11-31
Refer to this section for information on discovering the card stack according to the card type.
Enumerated Card Stack
The card stack performs the following tasks:
• Discovers the connected card
†
• Sets the relative Card Address Register (RCA) in the connected card
†
• Reads the card specific information
†
• Stores the card specific information locally
†
The card connected to the controller can be an MMC, CE-ATA, SD or SDIO (including IO ONLY, MEM
ONLY and COMBO) card.
Identifying the Connected Card Type
To identify the connected card type, the following discovery sequence is needed:
1. Reset the card width 1 or 4 bit (
card_width2
) and card width 8 bit (
card_width1
) fields in the
ctype
register to 0.
2. Identify the card type as SD, MMC, SDIO or SDIO-COMBO:
Altera Corporation
SD/MMC Controller
11-31
Enumerated Card Stack
cv_54011
2013.12.30