SanDisk SD032 Manual descarregar pdf (Página 12)

In addition, the miniSD host can read the card’s CID register using the READ_CID SD Card command. The CID

miniSD host can only read this register and not write to it.

An internal pull-up resistor on the DAT3 line may be used for card detection (insertion/removal). The resistor can be

disconnected during data transfer (using ACMD42). Additional practical card detection methods can be found in SD

Physical Specification’s Application Notes given by the SDA.

1.5.9.4. Card Status

The card status is separated into the following two fields:

• Card Status is stored in a 32-bit status register that 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.

• SD_Status is stored in 512 bits that are sent as a single data block after it was requested by the host

using the SD_STATUS (ACMD13) command. SD_STATUS contains extended status bits that relate

to BUS_WIDTH, security related bits and future specific applications.

1.5.9.5. Memory Array Partitioning

The basic unit of data transfer to/from the miniSD is one byte. All data transfer operations which require a block

size always define block lengths as integer multiples of bytes. Some special functions need other partition

granularity. Figure 1-2 shows the Memory Array Partitioning.

For block-oriented commands, the following definition is used:

• Block—The unit that is related to the block-oriented read and write commands. Its size is the number

of bytes that are transferred when one block command is sent by the host. The size of a block is either

programmable or fixed. The information about allowed block sizes and the programmability is stored

in the CSD.

The granularity of the erasable units is in general not the same as for the block-oriented commands:

• Sector—The unit that is related to the erase commands. Its size is the number of blocks that are erased

in one portion. The size of a sector is fixed for each device. The information about the sector size (in

blocks) is stored in the CSD.

For devices that include write protection, the following definition is used:

• WP Group—The minimal unit that may which may have individual write protection. Its size is the

number of groups which will be write protected by one bit. The size of a WP-group is fixed for each

device. The information about the size is stored in the CSD.

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SanDisk SD032 Manual Página 12