SanDisk SDMB-16-771 Product Manual - Page 48

MultiMediaCard Product Manual 5.7.2 Command Format (Command length 48 bits, 2.4 µs @ 20 MHz) 0 1 bit 5...bit 0 bit 31...bit 0 start bit host command argument Commands and arguments are listed in Table 5-3 through Table 5-9. 7-bit CRC Calculation: G(x) = x7 + x3 + 1 M(x) = (start bit)∗x39 + (host bit)∗x38 +...+ (last bit before CRC)∗x0 CRC[6...0] = Remainder[(M(x)∗x7)/G(x)] bit 6...bit 0 CRC71 5.7.3 Command Classes 1 end bit The command set of the MultiMediaCard is divided into several classes (See Table 5-2). Each class supports a set of MultiMediaCard functions. The supported Card Command Classes (CCC) are coded as a parameter in the card specific data (CSD) register of each card, providing the host with information on how to access the card. Table 5-2 Card Command Classes (CCCs) Card Command Class (CCC) Class Description Supported Commands 0 1 2 3 4 7 9 10 11 12 13 15 16 17 18 20 Class 0 Basic Class 1 Stream Read + Class 2 Block Read +++ Class 3 Stream Write + Class 4 Block Write + Class 5 Erase Class 6 Write Write-Protection Class 7 Read Write-Protection Class 8 Erase Write-Protection Class 9 I/O Mode2 Class 10-11 Reserved 1) 7-bit Cyclic Redundancy Check. 2) I/O mode class is not supported by the SanDisk MultiMediaCard. 48 SanDisk MultiMediaCard Product Manual Rev. 2 © 2000 SANDISK CORPORATION