Texas Instruments AM335 Series Technical Reference Manual

cmd
dat0
Command
Response
Command
Response
Data stop operation
Block write operation
Host to
card
Card to
host
Host to
card
Multiple block write operation
dat[3:1]
Card to
host
Data block
+ CRC
Busy
Busy
CRC
Status
XX
Host to
card
Card to
host
Data block
+ CRC
XXXX
Data block
+ CRC
Data block
+ CRC
CRC
Status
XX XXXX
cmd
dat[3:0]
Command
Response
Command
Response
Data stop operationBlock read operation
Host to
card
Card to
host
Card to
host
Multiple block read operation
Data block + CRC
Data block + CRC
Host to
card
Card to
host
Functional Description www.ti.com
Figure 18-8 and Figure 18-9 show how multiple block-oriented operations are defined. A multiple block-
oriented operation sends a data block plus CRC bits. The transfer terminates when a stop command
follows on the mmc_cmd line. These operations are available for all kinds of cards.
Figure 18-8. Multiple Block Read Operation (MMC Cards Only)
Figure 18-9. Multiple Block Write Operation (MMC Cards Only)
NOTE:
1. The card busy signal is not always generated by the card; the previous examples show
a particular case.
2. It is the software's responsibility to do a software reset after a data timeout to ensure
that mmc_clk is stopped. The software reset is done by setting bit 26 in the
SD_SYSCTL register to 1.
3. For multiblock transfer, and especially for MMC cards, you can abort a transfer without
using a stop command. Use a CMD23 before a data transfer to define the number of
blocks that will be transferred, then the transfer stops automatically after the last block
(provided the MMC card supports this feature).
3354
Multimedia Card (MMC) SPRUH73H–October 2011–Revised April 2013
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Texas Instruments AM335 Series Specifications

General

Brand	Texas Instruments
Model	AM335 Series
Category	Computer Hardware
Language	English