cmd
dat0
Command
Response
Command
Response
Data stream
Data stop operation
Data transfer operation
Host to
card
Card to
host
Host to
card
Card to
host
Busy
Host to
card
Card to
host
cmd
dat0
Command
Response
Command
Response
Data stream
Data stop operation
Data transfer operation
Card to
host
Host to
card
Card to
host
Card to
host
Host to
card
Functional Description
18.3.1.2.1 Protocol
There are two types of data transfer:
•
Sequential operation
•
Block-oriented operation
There are specific commands for each type of operation (sequential or block-oriented). See the Multimedia
Card System Specification, the SD Memory Card Specifications, and the SDIO Card Specification, Part E1
for details about commands and programming sequences supported by the MMC, SD, and SDIO cards.
CAUTION
Stream commands are supported only by MMC cards.
and
show how sequential operations are defined. Sequential operation is only for
1-bit transfer and initiates a continuous data stream. The transfer terminates when a stop command
follows on the mmc_cmd line.
Figure 18-6. Sequential Read Operation (MMC Cards Only)
Figure 18-7. Sequential Write Operation (MMC Cards Only)
3353
SPRUH73H – October 2011 – Revised April 2013
Multimedia Card (MMC)
Copyright © 2011–2013, Texas Instruments Incorporated