SanDisk SD Card

Revision 2.2Chapter 5 – SPI ProtocolSD Card Product ManualFigure 5-2Read Operation—Data ErrorFrom Hostto CardDataInCommandFrom Cardto HostNext CommandData ErrorToken fromCard to HostCommandDataOutResponseData ErrorIn the case of a Multiple Block Read operation, every transferred block has a 16-bit CRCsuffix. The Stop Transmission command (CMD12) will actually stop the data transferoperation (the same as in SD Bus mode).Figure 5-3 Multiple Block Read OperationFrom hostto card(s)DataInCommandFrom cardto hostData fromcard to hostCommandStopTransmissioncommandFrom cardto hostDataOutResponse Data Block CRC Data Block CRCResponse5.5 Data WriteIn SPI mode, the SD Card supports single block or multiple-block write operations. Uponreception of a valid write command (SD Card CMD24 or CMD25), the card will respondwith a response token and will wait for a data block to be sent from the host. CRC suffixand start address restrictions are identical to the read operation (see Figure 5-4). The onlyvalid block length, however, is 512 bytes. Setting a smaller block length will cause a writeerror on the next write command.Figure 5-4 Single Block Write OperationFrom hostto cardFrom cardto hostStart blocktokenData fromhost tocardDataresponseand busyfrom cardNewcommandfrom hostDataInCommandData BlockCommandDataOutResponseResponseBusy© 2004 SanDisk Corporation 5-3 12/08/04