SanDisk SD032 Manual descarregar pdf (Página 9)

The performance of the communication channel is described in Table 1-3.

Table 1-3. SD Bus/SPI Bus Comparison

miniSD Card Using SD Bus miniSD Card Using SPI Bus

Six-wire communication channel (clock, command, 4

data lines).

Three-wire serial data bus (Clock, dataIn, dataOut) + card

specific CS signal (hardwired card selection).

Error-protected data transfer. Optional non-protected data transfer mode available.

Single or multiple block oriented data transfer. Single or multiple block oriented data transfer.

1.4. miniSD Card Standards

SanDisk miniSD Cards are fully compatible with the miniSD Card Physical Layer Specification standard:

mini SD Physical Layer System Specification, Version 1.02

This specification may be obtained from:

SD Card Association

53 Muckelemi St.

P.O. Box 189

San Juan Bautista, CA 95045-0189

USA

Phone: 831-623-2107

Fax: 831-623-2248

www.sdcard.org

1.5. Functional Description

SanDisk miniSD Cards contain a high level, intelligent subsystem as shown in Figure 1-1. This intelligent

(microprocessor) subsystem provides many capabilities not found in other types of memory cards. These

capabilities include:

• Host independence from details of erasing and programming flash memory.

• Sophisticated system for managing defects (analogous to systems found in magnetic disk drives).

• Sophisticated system for error recovery including a powerful error correction code (ECC).

• Power management for low power operation.

1.5.1. Flash Technology Independence

The 512-byte sector size of the miniSD Card is the same as that in an IDE magnetic disk drive. To write or read a

sector (or multiple sectors), the host computer software simply issues a Read or Write command to the miniSD

Card. This command contains the address. The host software then waits for the command to complete. The host

software does not get involved in the details of how the flash memory is erased, programmed or read. This is

extremely important as flash devices are expected to get more and more complex in the future. Because the miniSD

Card uses an intelligent on-board controller, the host system software will not require changing as new flash

memory evolves. In other words, systems that support the miniSD Card today will be able to access future SanDisk

miniSD Cards built with new flash technology without having to update or change host software.

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SanDisk SD032 Manual Página 9