Browse Prior Art Database

Method for a host controller that eliminates unused pins when supporting multiple SD/SDIO/MMC devices

IP.com Disclosure Number: IPCOM000124317D
Publication Date: 2005-Apr-15
Document File: 3 page(s) / 63K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a host controller that eliminates unnecessary pins when supporting multiple secure digital (SD)/secure digital input/output (SDIO)/multimediacard (MMC) devices. Benefits include improved functionality and improved cost effectiveness.

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Method for a host controller that eliminates unused pins when supporting multiple SD/SDIO/MMC devices

Disclosed is a method for a host controller that eliminates unnecessary pins when supporting multiple secure digital (SD)/secure digital input/output (SDIO)/multimediacard (MMC) devices. Benefits include improved functionality and improved cost effectiveness.

Background

      Several specifications apply to the devices described in this disclosure, including the following:

•             "SDMI Portable Device Specification Part 1" Version 1.0, July 1999 and amended June 5, 2001 is owned by Secure Digital Music Initiative.

•             "SD Input/Output (SDIO) Card Specification" Version 1.00, October 2001 is owned by SD Card Association.

•             "MultiMediaCard Specification" Version 4.0, February 2, 2004 is owned by MultiMediaCard Association.

•             "Part 1 SD Memory Card Physical Layer Specification" Version 1.01, April 15, 2001 is owned by SD Card Association.

              The SDMI physical layer specification requires that multiple SD/SDIO cards be connected using a star topology with the DAT<3:0> and CMD signals duplicated on the host controller (see Figure 1).

Description

              The disclosed method is a host controller that eliminates unused pins when supporting multiple SD/SDIO/MMC devices. The method includes a pseudo-bus topology using the SD communication protocol included in the physical layer specification (see Figure 2).

              The communication protocol enables a bus topology but reduces total bandwidth by supporting serial transfer and not 4-bit data transfer. As a result, the DAT<2> and DAT<1> pins are not requi...