Realtek Semiconductor Corp.
Downloaded by Ally Chiang Realtek Semiconductor Corp. on 03/28/2012
©Copyright 2000-2012 SD Card Association
SDIO Specification Version 4.00
iv Confidential
Table of Contents
1. General Description ............................................................................................................ 1
1.1 Definitions ...................................................................................................................................... 1
1.1.1 SDIO Card ............................................................................................................................... 1
1.1.2 Embedded SDIO ..................................................................................................................... 1
1.2 SDIO Features ............................................................................................................................... 1
1.2.1 Common SDIO Features ......................................................................................................... 1
1.2.2 SDIO Card Features ............................................................................................................... 2
1.2.3 Embedded SDIO Device Features .......................................................................................... 2
1.3 Document Structure ....................................................................................................................... 3
1.4 Standard SDIO Functions .............................................................................................................. 3
2. SDIO Signaling Definition .................................................................................................. 4
2.1 SDIO Card Types .......................................................................................................................... 4
2.2 SDIO Card Modes ......................................................................................................................... 4
2.2.1 SPI Mode (Card mandatory support) ...................................................................................... 4
2.2.2 1-bit SD Data Transfer Mode (Card Mandatory Support) ........................................................ 4
2.2.3 4-bit SD Data Transfer Mode (Mandatory for High-Speed Cards, Optional for Low-Speed) ... 4
2.2.4 UHS-II Data Transfer Mode ..................................................................................................... 5
2.3 SDIO Host Modes .......................................................................................................................... 5
2.4 Signal Pins ..................................................................................................................................... 5
2.4.1 Signal Pins for SD Bus Interface SDIO Card .......................................................................... 5
2.4.2 Signal Pins for UHS-II Interface SDIO Card ............................................................................ 6
2.5 Host Requirements for SDIO ......................................................................................................... 6
2.5.1 SD Bus Interface ..................................................................................................................... 6
3. SDIO Card Initialization ...................................................................................................... 8
3.1 Initialization Sequence ................................................................................................................... 8
3.1.1 Initialization by Non-I/O Aware Host ........................................................................................ 8
3.1.2 Initialization by I/O Aware Host ............................................................................................... 9
3.2 The IO_SEND_OP_COND Command (CMD5) ........................................................................... 15
3.3 The IO_SEND_OP_COND Response (R4) ................................................................................. 16
3.4 Special Initialization Considerations for Combo Cards ................................................................ 17
3.4.1 Re-initialize Both I/O and Memory ........................................................................................ 17
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