Host Controllers

Introduction of SD Card Host Controller for
SD Card Promotion

What is the host controller?

SD Host Controller Ver.1.00 was introduced in 2004 as
a standard controller to manage SD Cards (SD Memory
and SDIO).
SD Host Controller was implemented not only mobile
devices but also PCs with Windows native support that
contributed to spread SD Memory Card market.
In this way, most Note PCs mounted Standard Size SD
Card Slots.

SD Card access by applications is converted to a
sequence of SD commands by SD Memory Driver and
SDIO Driver.
Host Controller Driver (Common Bus Driver) sends
those SD commands to SD Card through the Host
Controller that is connected to PC system bus (PCIe).
Single SD Host Controller can manage multiple SD
Cards by supporting multiple SD Slots.



SD Host Controller Extension


SD Host Controller has been extended in connection with the Physical Layer
functions extension.
Major improvement aimed increase of data transfer rate by supporting higher SD bus
speed modes and Direct Memory Access (DMA)

SD Host Ver.2 supported ADMA2 that can handle scattered paging data in system
memory (scatter gather DMA).
SD Host Ver.3 supported UHS-I bus modes.
SD Host Ver.4 supported UHS-II bus modes, ADMA3 and 64-bit system addressing
ADMA3 can execute multiple of ADMA2 data transfers without intervention of Host
Driver by Descriptor programing.
Host Driver overhead is hidden behind data transfer. That is why AMDA3 can
achieve high efficiency data transfer.


What is the host controller?

Simplified Version of SD Host Controller Spec