Revision 1.0 MultiMediaCardRS-MultiMediaCard Product Manual
© 2004 SanDisk Corporation 4-2
051304
4.1 Card Identification Mode
While in Card Identification Mode, the host resets all the cards that are in Card Identification Mode, validates operation voltage range, identifies cards and asks them to
publish a Relative Card Address RCA. This operation is done to each card separately on its own command CMD line. All data communication in the Card Identification Mode
uses the CMD line only.
Figure 4-1 MultiMediaCard State Diagram—Card Identification Mode
4.1.1 Reset
GO_IDLE_STATE CMD0 is the software-reset command that sets each MultiMediaCard or RS-MultiMediaCard to Idle State regardless of the current state of the card. Cards
already in an inactive state are not affected by this command.
After power-on by the host, all cards are in Idle State, including the cards that were in Inactive State.
1
After power-on or CMD0, all card CMD lines are in input mode, waiting for the start bit of the next command. The cards are initialized with a default relative card address
RCA=0x0000 and with a default driver stage register setting lowest speed, highest driving current capability.
4.1.2 Operating Voltage Range Validation
The MultiMediaCard standard requires that all MultiMediaCards and RS-MultiMediaCards be able to establish communication with the host using any operating voltage between
VDD-min and VDD-max. However, during data transfer, minimum and maximum values
1
At least 74 clock cycles are required prior to starting bus communication.
Revision 1.0 MultiMediaCardRS-MultiMediaCard Product Manual
© 2004 SanDisk Corporation 4-3
051304
for VDD are defined in the CSD Register and may not cover the entire range. Card hosts are expected to read the card’s CSD Register and select the proper VDD values or reject the
card.
A MultiMediaCardRS-MultiMediaCard that stores the CID and CSD data in the payload memory can communicate this information only under data-transfer VDD conditions. This
means if the host and card have incompatible VDD ranges, the card will not be able to complete the identification cycle, nor to send CSD data.
SEND_OP_COND CMD1 is designed to provide card hosts with a mechanism to identify and reject cards that do not match the host’s desired VDD range. To accomplish this task,
the host sends the required VDD voltage window as the operand of this command. MultiMediaCardsRS-MultiMediaCards that cannot perform data transfer in the specified
range must discard themselves from further bus operations and go into Inactive State. All other cards will respond concurrently same method as card identification sending back
their VDD range. The wired-or result of the response will show all voltage ranges, some of which the cards do not support.
By omitting the voltage range in the command, the host can query the card stacks and determine if there are any incompatibilities before sending out-of-range cards into the
Inactive State. A bus query should be used if the host can select a common voltage range or wants to notify the application of unusable cards in the stack.
The MultiMediaCard or RS-MultiMediaCard can use the busy bit in the CMD1 response to tell the host that it is still working on the power-upreset procedure e.g., downloading the
register information from memory field and is not ready for communication. In this case the host must repeat CMD1 until the busy bit is cleared.
During the initialization procedure, the host is not allowed to change OCR values; the card will ignore OCR content changes. If there is a actual change in the operating conditions,
the host must reset the card stack using CMD0 and begin the initialization procedure again.
GO_INACTIVE_STATE CMD15 can also be used to send an addressed MultiMediaCardRS-MultiMediaCard into the Inactive State. CMD15 is used when the
host explicitly wants to deactivate a card—for example, the host changes VDD into a range not supported by this card.
4.1.3 Card Identification Process
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