MC12H064NBCA-2SA00 Datasheet, PDF (17/102 Pages) Samsung semiconductor – SAMSUNG MultiMediaCard

Revision 0.3
MultiMediaCard^TM
5.2.2 Power Protection
Cards shall be inserted/removed into/from the bus without damage. If one of the supply pins (V_DD or V_SS) is not connected
properly, then the current is drawn through a data line to supply the card. Every card’s output also shall be able to with-
stand shortcuts to either supply. If hot insertion feature is implemented in the host, than the host has to withstand a short-
cut between V_DD and V_SS without damage.
5.3 SPI Bus Topology
The SPI mode consists of a secondary, optional communication protocol which is offered by Flash-based MultiMedi-
aCards. This mode is a subset of the MultiMediaCard protocol, designed to communicate with a SPI channel. The Multi-
MediaCard SPI interface is compatible with SPI hosts available on the market. As in any other SPI device, the
MultiMediaCard SPI channel consists of the following four signals:
CS: Host to card Chip Select signal
CLK: Host to card clock signal
DataIn: Host to card data signal
DataOut: Card to host data signal
Another SPI common characteristic is byte transfers, which is implemented in the card as well. All data tokens are multi-
ples of bytes (8 bit) and always byte aligned to the CS signal.The SPI standard defines the physical link only, and not the
complete data transfer protocol.
The card identification and addressing methods are replaced by a hardware Chip Select (CS) signal. There are no broad-
cast commands. For every command, a card (slave) is selected by asserting (active low) the CS signal (see Figure ).
The CS signal must be continuously active for the duration of the SPI transaction (command, response and data). The
only exception occurs during card programming, when the host can de-assert the CS signal without affecting the program-
ming process.
The bidirectional CMD and DAT lines are replaced by unidirectional dataIn and dataOut signals. This eliminates the ability
to excute commands while data is being read or written which prevents swquential multi read/write operations. Only single
block read/write is supported by the SPI channel.
Power
supply
SPI bus
CS
master
SPI bus (CLK, DataIn, DataOut)
SPI
Card
5.3.1 Power Protection
Figure 5-2 : MultiMediaCard Bus System
Power protection is the same as it is in MultiMediaCard mode.
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Sep.22.2005