Atmel Evaluation Kit AT91SAM9M10-G45-EK AT91SAM9M10-G45-EK Data Sheet
Product codes
AT91SAM9M10-G45-EK
673
SAM9M10 [DATASHEET]
6355F–ATARM–12-Mar-13
Figure 35-6.
SD Card Bus Connections with One Slot
Note:
When several HSMCI (x HSMCI) are embedded in a product, MCCK refers to HSMCIx_CK, MCCDA to HSMCIx_CDA MCDAy
to HSMCIx_DAy.
to HSMCIx_DAy.
When the HSMCI is configured to operate with SD memory cards, the width of the data bus can be selected in the
HSMCI_SDCR register. Clearing the SDCBUS bit in this register means that the width is one bit; setting it means
that the width is four bits. In the case of High Speed MultiMedia cards, only the data line 0 is used. The other data
lines can be used as independent PIOs.
HSMCI_SDCR register. Clearing the SDCBUS bit in this register means that the width is one bit; setting it means
that the width is four bits. In the case of High Speed MultiMedia cards, only the data line 0 is used. The other data
lines can be used as independent PIOs.
35.8
High Speed MultiMedia Card Operations
After a power-on reset, the cards are initialized by a special message-based High Speed MultiMedia Card bus pro-
tocol. Each message is represented by one of the following tokens:
tocol. Each message is represented by one of the following tokens:
• Command: A command is a token that starts an operation. A command is sent from the host either to a single
card (addressed command) or to all connected cards (broadcast command). A command is transferred serially
on the CMD line.
on the CMD line.
• Response: A response is a token which is sent from an addressed card or (synchronously) from all connected
cards to the host as an answer to a previously received command. A response is transferred serially on the
CMD line.
CMD line.
• Data: Data can be transferred from the card to the host or vice versa. Data is transferred via the data line.
Card addressing is implemented using a session address assigned during the initialization phase by the bus con-
troller to all currently connected cards. Their unique CID number identifies individual cards.
troller to all currently connected cards. Their unique CID number identifies individual cards.
The structure of commands, responses and data blocks is described in the High Speed MultiMedia-Card System
Specification. See also
Specification. See also
.
High Speed MultiMediaCard bus data transfers are composed of these tokens.
There are different types of operations. Addressed operations always contain a command and a response token. In
addition, some operations have a data token; the others transfer their information directly within the command or
response structure. In this case, no data token is present in an operation. The bits on the DAT and the CMD lines
are transferred synchronous to the clock HSMCI Clock.
addition, some operations have a data token; the others transfer their information directly within the command or
response structure. In this case, no data token is present in an operation. The bits on the DAT and the CMD lines
are transferred synchronous to the clock HSMCI Clock.
Two types of data transfer commands are defined:
• Sequential commands: These commands initiate a continuous data stream. They are terminated only when a
stop command follows on the CMD line. This mode reduces the command overhead to an absolute minimum.
• Block-oriented commands: These commands send a data block succeeded by CRC bits.
Both read and write operations allow either single or multiple block transmission. A multiple block transmission is
terminated when a stop command follows on the CMD line similarly to the sequential read or when a multiple block
transmission has a pre-defined block count (
terminated when a stop command follows on the CMD line similarly to the sequential read or when a multiple block
transmission has a pre-defined block count (
).
The HSMCI provides a set of registers to perform the entire range of High Speed MultiMedia Card operations.
2345
6
17
MCDA0 - MCDA3
MCCDA
MCCK
8
SD CARD
9