AN 509: Multiplexing SDIO Devices Using Altera MAX Series

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ID 683683
Date 9/22/2014
Public
Document Table of Contents
Document Table of Contents x
1. Multiplexing SDIO Devices Using Altera MAX Series
1. Multiplexing SDIO Devices Using Altera MAX Series x
1.1. Using Multiple SD Devices 1.2. I2C Select Line Multiplexer Using MAX II Devices 1.3. Acknowledgments 1.4. Document Revision History
1.2. I2C Select Line Multiplexer Using MAX II Devices x
1.2.1. Design Demonstration on the MDN-B2 Demo Board 1.2.2. Setting up a Parallel Port Driven I2C Environment on PC 1.2.3. Setting up SD Host/Card Reader to Work with The MDN-B2 Demo Setup
1. Multiplexing SDIO Devices Using Altera MAX Series

1.1. Using Multiple SD Devices

It may often be required for an SD host controller with a single SD interface to support more than one SD device. The SD protocol and standards recommend doing this using one of following two methods:

  • Use a bidirectional multiplexer between the SD host and the multiple SD devices and use this multiplexer to multiplex the data lines. This is performed while the clock line is connected to each of the multiple SD devices.
  • Retain the data lines connected to the multiple SD devices while multiplexing the unidirectional clock line.

This design example uses the second method described above.

Figure 1. Implementing a Clock-Based SD MUX
Level Two Title