MC56U032DCCA Datasheet, PDF (47/64 Pages) Samsung semiconductor – Dual Voltage MultiMediaCard Specification

MultiMediaCard^TM
GO_IDLE_STATE (CMD0) is the software reset command, which sets the MultiMediaCard into the Idle
State independently of the current state. In the Inactive State the MultiMediaCard is not affected by this
command. After power-on the MultiMediaCard is always in the Idle State. After power-on or command
GO_IDLE_STATE (CMD0) all output bus drivers of the MultiMediaCard is in a high-impedance state and
the card will be initialized with a default relative card address (“0x0001”). The host runs the bus at the
identification clock rate fOD generated by a push-pull driver stage (refer to also Chapter “Power on” for
more details).
4.10 SPI Communication
The SPI mode consists of a secondary communication protocol. This mode is a subset of the
MultiMediaCard protocol, designed to communicate with a SPI channel, commonly found in Motorola’s
(and lately a few other vendors’) microcontrollers. The interface is selected during the first reset
command after power up (CMD0) and cannot be changed once the part is powered on. The SPI
standard defines the physical link only, and not the complete data transfer protocol. The
MultiMediaCard SPI implementation uses a subset of the MultiMediaCard protocol and command set.
It is intended to be used by systems which require a small number of card (typically one) and have
lower data transfer rates (compared to MultiMediaCard protocol based systems). From the application
point of view, the advantage of the SPI mode is the capability of using an off-the-shelf host, hence
reducing the design-in effort to minimum. The disadvantage is the loss of performance of the SPI
system versus MultiMediaCard (lower data transfer rate, fewer cards, hardware CS per card etc.).
While the MultiMediaCard channel is based on command and data bitstreams which are initiated by a
start bit and terminated by a stop bit, the SPI channel is byte oriented. Every command or data block is
built of 8-bit bytes and is byte aligned to the CS signal (i.e. the length is a multiple of 8 clock cycles).
Similar to the MultiMediaCard protocol, the SPI messages consist of command, response and data-
block tokens (refer to Chapter “Commands” and Chapter “Responses” for a detailed description). All
communication between host and cards is controlled by the host (master). The host starts every bus
transaction by asserting the CS signal low. The response behavior in the SPI mode differs from the
MultiMediaCard mode in the following three aspects:
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