---
title: Secure digital input/output interface (SDIO)
categories: SDIO, STM32F4
...

Introduction
============

What is SDIO?
-----------------
- A SDIO (Secure Digital Input Output) card is an extension of the SD specification to cover I/O functions. 
- Host devices that support SDIO can use the SD slot to support: 
   1.  GPS receivers.
   2.  digital cameras. 
   3.  RFID readers. 
   4.  FM radio tuners.
   5.  TV tuners. 
   6.  Wi-Fi.
   7.  Bluetooth. 

 Many other SDIO devices have been proposed, but it is now more common for I/O devices to connect using the USB interface.
- SDIO cards support most of the memory commands of SD cards. SDIO cards can be structured as 8 logical cards, although currently, the typical way that an SDIO card uses this capability is to structure itself as one I/O card and one memory card.

.. image:: /sdio1.png
.. image:: /sdio2.png

Difference of SD/MMC/SDIO
--------------------------



Speed class rating
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Reference
==========
- `Secure Digital wiki<http://en.wikipedia.org/wiki/Secure_Digital#SDIO>`_
- `SDIO接口介绍<http://en.wikipedia.org/wiki/Secure_Digital#SDIO>`_
-  `Linux（open source）的 SD/MMC/SDIO 支援現況概要<http://en.wikipedia.org/wiki/Secure_Digital#SDIO>`_
-  `SD/MMC/SDIO概念區分<http://en.wikipedia.org/wiki/Secure_Digital#SDIO>`_