SanDisk SD Card

Revision 2.2Chapter 5 – SPI ProtocolSD Card Product Manual5.17 SPI Command SetThe following sections provide valuable information on the SPI Command Set.5.17.1 Command FormatAll SD Card commands are six bytes long and transmitted MSB first.Byte 1 Byte 2-5 Byte 67 6 5 0 31 0 7 00 1 Command Command Argument CRC 1Commands and arguments are listed in Table 5-2.7-bit CRC Calculation: G(x) = x 7 + x 3 + 1M(x) = (start bit)*x 39 + (host bit)*x 38 +...+ (last bit before CRC)*x 0CRC[6...0] = Remainder[(M(x)*x 7 )/G(x)]5.17.2 Command ClassesAs in SD mode, the SPI commands are divided into several classes (See Table 5-1). Eachclass supports a set of card functions. A SD Card will support the same set of optionalcommand classes in both communication modes (there is only one command class table inthe CSD register). The available command classes, and the supported commands for aspecific class, however, are different in the SD Memory Card and the SPI communicationmode.Note that except the classes that are not supported in SPI mode (class 1, 3 and 9), themandatory required classes for the SD mode are the same for the SPI mode.Table 5-1 Command Classes in SPI ModeCCC 0 1 6 9 10 12 13 16 17 18 24 25 27 28 29 30 32 33 34 35 36 37 38 42 50 52 53 55 56 57 58 590 Basic + + + + + + + +1 NS2 Block read + + +3 NS4 Block write + + + +5 Erase + + +6 Writeprotect+ + +7 Lock card + +8 Appspecific+ +9 I/O mode + +10 Switch + + + + + + +11 RKey:NS = Not supported in SPI mode.R = Reserved© 2004 SanDisk Corporation 5-8 12/08/04