SMS512DFA5E NUMONYX, SMS512DFA5E Datasheet - Page 44

• Manufacturer Part Number: SMS512DFA5E
• Description: MICROSD CARD SMS 512MB FLASH MEM
• Manufacturer: NUMONYX

Specifications of SMS512DFA5E

• Memory Size: 512MB
• Memory Type: SD (Secure Digital)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Serial peripheral interface (SPI) mode
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Serial peripheral interface (SPI) mode
The SPI mode is a secondary communication protocol, which is available in flash memory-
based SD memory cards. The SD memory card SPI implementation uses a subset of the
SD memory card protocol and command set. The advantage of the SPI mode is the
capability of using off-the-shelf host, hence reducing the design-in effort to a minimum. The
disadvantage is the loss of performance (for instance, single data line and hardware CS
signal per card). The SPI mode is selected during the first Reset command after power-up
(CMD0) and cannot be changed once the part is powered on.
SPI bus topology
The SPI compatible communication mode of the SD memory card is designed to
communicate with an SPI channel, commonly found in various microcontrollers on the
market. The SPI standard defines the physical link only, and not the complete data transfer
protocol. The SD memory card SPI and SD modes use the same command set.
Like all SPI devices, the SD memory card SPI channel uses the four following signals:
All data tokens are multiples of bytes (8 bits) and always byte-aligned to the CS signal. The
card identification and addressing methods are replaced by a hardware Chip Select (CS)
signal. There are no broadcast commands. For every command, a card (slave) is selected
by asserting (active Low) the CS signal (see
bus
transaction. The only exception occurs during card programming, when the host can de-
assert the CS signal without affecting the programming process. The SPI interface uses 7
out of the 9 SD signals (DAT1 and DAT2 are not used, DAT3 is the CS signal) of the SD bus.
topology). The CS signal must be continuously active for the duration of the SPI
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.
Figure 32: SD memory card system SPI mode
SMSxxxDF