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©Copyright 2000-2007 SD Card Association
SDIO Simplified Specification Version 2.00
34
Field
Type
Description
SMPC
R/O
Support Master Power Control These bits tell the host if the card supports Master
Power Control.
SMPC=0 : The total card current is less than 200mA, even if all functions
are active (IOEx=1). EMPC,SPS and EPS shall be zero.
SMPC=1 :The total card current may exceed 200mA.
EMPC, SPS and EPS are available.
EMPC
R/W
Enable Master Power Control
EMPC=0(default): The total card current shall be less than 200mA.
The card automatically switches the mode of function(s) to lower current or does not
allow some functions to become enabled, regardless of the value of EPS, so that total
card current is 200mA or less. (The card manufacturer determines which functions
operate and their modes to guarantee this limit.)
EMPC=1: The total card current may exceed 200mA and SPS and EPS are available.
The host uses SPS, EPS in FBR and IOEx to enable higher current function modes
based on the host’s ability to supply the necessary current.
SHS R/O
Support
High-Speed
This flag bit reports the card’s ability to operate in High-Speed mode
SHS=0: The card does not support High-Speed mode
SHS=1: The card supports High-Speed mode. The host enables High-Speed mode
via the EHS bit. See section 12 for details on switching between default and
High-Speed mode.
EHS R/W
Enable
High-Speed
EHS=0 (default): The card operates in default timing mode with a clock rate up to
25MHz.
EHS=1 : High-Speed Mode
The card operates in High-Speed timing mode with a clock rate up to 50MHz. See
section 12 for details on switching between default and High-Speed mode.
When SHS is set to 0, writing to this bit is ignored and always indicates 0.
RFU
R/O
Any bit defined as Reserved for Future Use (RFU) shall be read-only and shall be
read as 0.
Reserved
for Vendors
R/W
These 16 registers are reserved for the maker of the I/O card to be used for any
operations that are defined by and specific to any vendor unique operation.
Information about the use of these optional registers needs to be obtained from the
SDIO card maker. Reading and/or writing these registers without understanding the
vendor’s definitions may cause unexpected behavior or even damage to the card.
Table 6-2 CCCR bit Definitions