©Copyright 2000-2007 SD Card Association
SDIO Simplified Specification Version 2.00
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Table of Contents
1. General Description ................................................................................................................................. 1
1.1 SDIO Features .................................................................................................................................... 1
1.2 Primary Reference Document ............................................................................................................. 1
1.3 Standard SDIO Functions.................................................................................................................... 1
2. SDIO Signaling Definition........................................................................................................................ 2
2.1 SDIO Card Types ................................................................................................................................ 2
2.2 SDIO Card modes............................................................................................................................... 2
2.2.1 SPI (Card mandatory support) ..................................................................................................... 2
2.2.2 1-bit SD Data Transfer Mode (Card Mandatory Support) ............................................................. 2
2.2.3 4-bit SD Data Transfer Mode (Mandatory for High-Speed Cards, Optional for Low-Speed)......... 2
2.3 SDIO Host Modes ............................................................................................................................... 2
2.4 Signal Pins .......................................................................................................................................... 3
3. SDIO Card Initialization............................................................................................................................ 4
3.1 Differences in I/O card Initialization ..................................................................................................... 4
3.2 The IO_SEND_OP_COND Command (CMD5)................................................................................. 10
3.3 The IO_SEND_OP_COND Response (R4)........................................................................................11
3.4 Special Initialization considerations for Combo Cards....................................................................... 12
3.4.1 Re-initialize both I/O and Memory .............................................................................................. 12
3.4.2 Using a Combo Card as SDIO only or SD Memory only after Combo Initialization.................... 12
3.4.3 Acceptable Commands after Initialization .................................................................................. 12
3.4.4 Recommendations for RCA after Reset ..................................................................................... 12
3.4.5 Enabling CRC in SPI Combo Card............................................................................................. 14
4. Differences with SD Memory Specification.......................................................................................... 15
4.1 SDIO Command List ......................................................................................................................... 15
4.2 Unsupported SD Memory Commands............................................................................................... 15
4.3 Modified R6 Response ...................................................................................................................... 16
4.4 Reset for SDIO.................................................................................................................................. 16
4.5 Bus Width.......................................................................................................................................... 16
4.6 Card Detect Resistor......................................................................................................................... 17
4.7 Timings.............................................................................................................................................. 17
4.8 Data Transfer Block Sizes ................................................................................................................. 18
4.9 Data Transfer Abort ............................................................................................................
............... 18
4.9.1 Read Abort ................................................................................................................................. 18
4.9.2 Write Abort ................................................................................................................................. 18
4.10 Changes to SD Memory Fixed Registers .......................................................................................... 18
4.10.1 OCR Register............................................................................................................................. 19
4.10.2 CID Register............................................................................................................................... 19
4.10.3 CSD Register ............................................................................................................................. 19
4.10.4 RCA Register ............................................................................................................................. 19
4.10.5 DSR Register ............................................................................................................................. 19
4.10.6 SCR Register ............................................................................................................................. 19
4.10.7 SD Status ................................................................................................................................... 19
4.10.8 Card Status Register .................................................................................................................. 19
5. New I/O Read/Write Commands............................................................................................................ 21
5.1 IO_RW_DIRECT Command (CMD52) .............................................................................................. 21
5.2 IO_RW_DIRECT Response (R5) ......................................................................................................22
5.2.1 CMD52 Response (SD modes).................................................................................................. 22
5.2.2 R5, IO_RW_DIRECT Response (SPI mode) ............................................................................. 23
5.3 IO_RW_EXTENDED Command (CMD53) ........................................................................................ 24
5.3.1 CMD53 Data Transfer Format .................................................................................................... 25
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