Portion A
32 bits
Portion B
32 bits
128 words
Interconnect clock domain
Interface (card) clock domain
2’
2
1’
1
Write to
SD_DATA
Write to card
2
occurs only after
1
2
When
is completed, 2’
occurs only after
1’
Portion A
32 bits
Portion B
32 bits
128 words
128 words
Write to
SD_DATA
Write to card
are two different transfers that occur at the same time.
and
Write
to
the card
SD_CMD[DDIR]=0
Interconnect bus
Interconnect bus
Card bus
Card bus
MEM_SIZE/8
Functional Description
CAUTION
The SD_CMD[4] DDIR bit must be configured before a transfer to indicate the
direction of the transfer.
shows the buffer management for writing and
shows the buffer management
for reading.
Figure 18-19. Buffer Management for a Write
3367
SPRUH73H – October 2011 – Revised April 2013
Multimedia Card (MMC)
Copyright © 2011–2013, Texas Instruments Incorporated