Datasheet

551

SAM9261 [DATASHEET]

Atmel-6062O-ATARM-SAM9261-Datasheet_21-Jun-16

Notes: 1. I: input, O: output, PP: Push Pull, OD: Open Drain.

2. When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to MCIx_CDA,

MCDAy to MCIx_DAy.

Figure 34-6. SD Card Bus Connections with One Slot

Note: When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to MCIx_CDA MCDAy to

MCIx_DAy.

When the MCI is configured to operate with SD memory cards, the width of the data bus can be selected in the

MCI_SDCR. 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 multimedia cards, only the data line 0 is used. The other data lines can be used as

independent PIOs.

34.8 MultiMedia Card Operations

After a power-on reset, the cards are initialized by a special message-based MultiMedia Card bus protocol. 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.

 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.

 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

controller to all currently connected cards. Their unique CID number identifies individual cards.

The structure of commands, responses and data blocks is described in the MultiMedia-Card System Specification.