SDMJ-32 SanDisk, SDMJ-32 Datasheet - Page 69

• Manufacturer Part Number: SDMJ-32
• Manufacturer: SanDisk
• Type: MultiMedia Cardr

Specifications of SDMJ-32

• Density: 32MByte
• Operating Supply Voltage (typ): 3.3V
• Operating Temperature (min): -25C
• Operating Temperature (max): 85C
• Package Type: MMC
• Mounting: Socket
• Pin Count: 7
• Operating Temperature Classification: Commercial
• Operating Supply Voltage (min): 2.7V
• Operating Supply Voltage (max): 3.6V
• Programmable: Yes
• Lead Free Status / RoHS Status: Compliant

Revision 1.3
© 2005 SanDisk Corporation
5.6
5.7
Bus Transfer Protection
Data Read
(CS signal low), the module will switch to SPI mode and respond with the SPI mode R1
response.
The only way to return to MultiMediaCard mode is by a power cycle (turning the power off
and on). In SPI mode, the MultiMediaCard protocol state machine is not observed. All of
the MultiMediaCard commands supported in SPI mode are always available.
CRC bits protect every MultiMediaCard/RS-MultiMediaCard token transferred on the bus.
In SPI mode, the card offers a non-protected mode that enables systems built with reliable
data links to exclude the hardware or firmware required for implementing the CRC
generation and verification functions.
The SPI interface is initialized in the non-protected mode. However, the RESET command
(CMD0), which is used to switch the card to SPI mode, is received by the card while in
MultiMediaCard mode and, therefore, must have a valid CRC field.
Since CMD0 has no arguments, the content of all the fields, including the CRC field, are
constants and need not be calculated in run time. A valid reset command is:
The host can turn the CRC option on and off using the CRC_ON_OFF command
(CMD59).
SPI Mode supports single block and multiple-block read operations The main difference
between SPI and MultiMediaCard modes is that the data and the response are both
transmitted to the host on the DataOut signal. Therefore, the card response to the
STOP_COMMAND might end abruptly and replace the last data block. (Figure 5-2).
Figure 5-2
The basic unit of data transfer is a block whose maximum size is defined in the CSD
(READ_BL_LEN). If READ_BL_PARTIAL is set, smaller blocks whose starting and
ending address are entirely contained within one physical block (as defined by
READ_BL_LEN) may also be transmitted. A CRC is appended to the end of each block
ensuring data transfer integrity. CMD17 (READ_SINGLE_BLOCK) initiates a single
block read.
CMD18 (READ_MULTIPLE_BLOCK) starts a transfer of several consecutive blocks. The
number of blocks for the multiple block read operation is not defined. The card will
continuously transfer data blocks until a stop transmission command is received.
DataIn
DataOut
0x40, 0x0, 0x0, 0x0, 0x0, 0x95
From Host
to Card
Command
Single Block Read Operation
Response
5-4
MultiMediaCard/RS-MultiMediaCard Product Manual
From Card
to Host
Data Block
Next Command
CRC
Data from
Card to Host
Chapter 5 –SPI Mode
Command
04/21/05