MultiMediaCardTM
An important feature of the MultiMediaCard is automatic entrance and exit from sleep mode. Upon
completion of an operation, the MultiMediaCard will enter the sleep mode to conserve power if no
further commands are received within 5 msec The host does not have to take any action for this to
occur. In most systems, the MultiMediaCard is in sleep mode except when the host is accessing it,
thus conserving power. When the host is ready to access the MultiMediaCard and it is in sleep mode,
any command issued to the MultiMediaCard will cause it to exit sleep and respond. The host does not
have to issue a reset first. It may do this if desired, but it is not needed. By not issuing the reset,
performance is improved through the reduction of overhead.
2.5 Hot Insertion
Support for hot insertion will be required on the host but will be supported through the connector.
Connector manufacturers will provide connectors that have power pins long enough to be powered
before contact is made with the other pins. Please see connector data sheets for more details. This
approach is similar to that used in PCMCIA to allow for hot insertion. This applies to both
MultiMediaCard and SPI modes.
2.6 MultiMediaCard Mode
2.6.1 MultiMediaCard Standard Compliance
The MultiMediaCard is fully compliant with MultiMediaCard standard specification V3.31.
The structure of the Card Specific Data (CSD) register is compliant with CSD structure V1.2.
2.6.2 Negotiating Operation Conditions
The MultiMediaCard supports the operation condition verification sequence defined in the
MultiMediaCard standard specifications. The MultiMediaCard host should define an operating voltage
range that is not supported by the MultiMediaCard. It will put itself in an inactive state and ignore any
bus communication. The only way to get the card out of the inactive state is by powering it down and
up again. In addition the host can explicitly send the card to the inactive state by using the
GO_INACTIVE_STATE command.
2.6.3 Card Acquisition and Identification
The MultiMediaCard bus is a single master (MultiMediaCard host) and multi-slaves (cards) bus. The
host can query the bus and find out how many cards of which type are currently connected. The
MultiMediaCard’s CID register is pre-programmed with a unique card identification number which is
used during the acquisition and identification procedure
In addition, the MultiMediaCard host can read the card’s CID register using the READ_CID
MultiMediaCard command. The CID register is programmed during the MultiMediaCard testing and
formatting procedure, on the manufacturing floor. The MultiMediaCard host can only read this register
and not write to it.
2.6.4 Card Status
MultiMediaCard status is stored in a 32 bit status register which is sent as the data field in the card
respond to host commands. Status register provides information about the card’s current state and
completion codes for the last host command. The card status can be explicitly read (polled) with the
SEND_STATUS command.
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