
©Copyright 2000-2007 SD Card Association
SDIO Simplified Specification Version 2.00
30
Field
Type
Description
SDx
R/O
SD Format Version number. These 4 bits contain the version of the SD Physical
Specification that this card supports. The codes for the SD Physical Specification are
as follows:
Value SD Physical Specification
0x00
SD Physical Specification Version 1.01 (March 2000)
0x01
SD Physical Specification Version 1.10 (October 2004)
0x02
SD Physical Specification Version 2.00 (May 2006)
0x03-0x0F
Reserved for Future Use
IOEx
R/W
Enable Function - If this bit is reset to 0, the function is disabled. If this bit is set to 1,
the function is enabled to start its initialization. The completion of initialization is
indicated in IORx. On power up or after a reset, the card shall reset this bit to 0. The
host can also use IOEx as a per function reset for error recovery. The host sequence
for a per function reset is to reset IOEx to 0, wait until IORx becomes 0 and then set
IOEx to 1 again. If the error is not recovered by this sequence, SDIO reset should be
used noting that the operation of all functions will be aborted. See section 11 for
relation to Master Power Control and Power Select.
IORx
R/O
I/O Function Ready- If this bit is reset to 0, the function is not ready to operate. This
may be caused by the function being disabled or not ready due to internal causes
such as a built-in self-test in progress. If this bit is set to 1, the function is ready to
operate. The functions shall set this bit to 1 within the timeout value defined in the
TPLFE_ENABLE_TIMEOUT_VAL tuple. On power up or after a reset, this bit shall
be set to 0. For any function that is not implemented on an SDIO card, this bit shall
always be 0.
IENx
R/W
Interrupt Enable for function x. If this bit is cleared to 0, any interrupt from this function
shall not be sent to the host. If this bit is set to 1, then this function’s interrupt shall be
sent to the host if the master Interrupt Enable (bit 0) is also set to 1.
IENM
R/W
Interrupt Enable Master. If this bit is cleared to 0, no interrupts from this card shall be
sent to the host. If this bit is set to 1, then any function’s interrupt shall be sent to the
host.
INTx
R/O
Interrupt Pending for function x. If this bit is cleared to 0, this indicates that no
interrupts are pending from this function. If this bit is set to 1, then this function has
interrupt pending. Note that if the IENx
or
IENM bits are not set, the host cannot
receive this pending interrupt.
ASx
W/O
Abort Select In order to abort an I/O read or write and free the SD bus, the function
that is currently transferring data must be addressed. These 3 bits define which
function’s transfer to stop. For example, the abort the transfer to function number 3,
the value of 0x03 would be written to these bits using CMD52 only. If the abort is
addressed to a suspended function, it does not affect current data transaction. Note
that this is an abort, not a reset. The addressed function shall return to the CMD state
and data transfer pending to that function shall be halted. This abort procedure does
not work for SPI write operations. To abort an SPI write data transfer use the
STOP_TRAN token as defined in section 7.3.3 of the SD Physical Specification. This
form of abort applies only to the functions of an SDIO card. For the memory of a
combo card, the abort methods defined in the SD Physical Specification shall be used
to abort transfers to/from memory
RES
W/O
I/O CARD RESET: Setting the RES to 1 shall cause all I/O functions in an SDIO or
Combo card to perform a soft reset. Setting the RES to 1 does not affect the current
card protocol selection(SD vs. SPI mode) and CD Disable. Setting of the RES bit
shall only be performed using CMD52. When RES=1, the values of AS2-0 are
don’t-cares. The RES bit is auto cleared, so there is no need to rewrite a value of 0.
This bit is write-only, any read returns an undetermined value. Memory in a combo
card is not affected.