SanDisk SD Card - OEM Product Manual

Introduction

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Table 1-1 contains descriptions for each transfer mode.

Table 1-1 Mode Definitions

Mode

Description

Single Block

In this mode the host reads or writes one data block in a pre-specified length.

The data block transmission is protected with 16-bit CRC that is generated by

the sending unit and checked by the receiving unit. The block length for read

operations is limited by the device sector size (512 bytes) but can be as small

as a single byte. Misalignment is not allowed. Every data block must be

contained in a single physical sector. The block length for write operations

must be identical to the sector size and the start address aligned to a sector

boundary.

Multiple Block

This mode is similar to the single block mode, except for the host can read/

write multiple data blocks (all have the same length) that are stored or

retrieved from contiguous memory addresses starting at the address specified

in the command. The operation is terminated with a stop transmission

command. Misalignment and block length restrictions apply to multiple blocks

and are identical to the single block read/write operations.

1.7

SPI Mode

The SPI Mode is a secondary communication protocol for the SD card. This mode is a subset

of the SD Protocol, designed to communicate with an SPI channel, commonly found in

Motorola and other vendors' microcontrollers. Detailed information about SPI Mode can be

found in Section 7 or the SDA Physical Layer Specification, Version 3.01.