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©Copyright 2000-2007 SD Card Association
SDIO Simplified Specification Version 2.00
19
4.10.1 OCR
Register
All SD cards (memory, I/O and combo) shall have at least one OCR register. If the card is a combo card, it
may
have two OCR’s (one for memory and one for I/O). The memory portion of a combo card has an OCR accessed
using ACMD41 and CMD58. The I/O portion of a card has an OCR with the same structure that is accessed via
CMD5. If there are multiple OCR’s the voltage range may not be identical. Some I/O functions may have a wider
VDD range than that reflected in the I/O OCR register. The I/O OCR shall be the logical AND of the voltage
ranges(s) of all I/O functions. Note that the I/O OCR format is different from the memory version in that it is only
24 bits long. For details, see Table 3-1. The per-function voltage for each I/O function can be read in the CIS for
the card.
4.10.2 CID
Register
There shall be a
maximum
of one CID register per SD card. If the card contains both memory and I/O, the CID
register information is unchanged from the SD 1.01 version and reflects the information from the memory
portion of the card. If the card is I/O only, the CID register and the associated access command (CMD10) are
not
supported. If the host attempts to access this register in an I/O only card, a card in SPI mode shall respond
with an "Invalid Command" error response and a card in SD mode shall not respond.
4.10.3 CSD
Register
There shall be a
maximum
of one CSD register per SD card. If the card contains both memory and I/O, the CSD
register information is unchanged from the SD 1.01 version and reflects the information from the memory
portion of the card. If the card is I/O only, the CSD register and the associated access command (CMD9) are
not
supported. If the host attempts to access this register in an I/O only card, a card in SPI mode shall respond with
an "Invalid Command" error response and a card in SD mode shall not respond.
4.10.4 RCA
Register
There shall only be one RCA register per SD card. The RCA value shall apply to the card as a whole. All
functions and any memory share the same card address.
4.10.5 DSR
Register
SDIO only cards do not support the DSR register. In the case of combo cards, support is optional as defined in
the SD Physical Specification.
4.10.6 SCR
Register
There shall be a
maximum
of one SCR register per SD card. If the card contains both memory and I/O, the SCR
register information is unchanged from the SD 1.01 version and reflects the information from the memory
portion of the card. If the card is I/O only, the SCR register and the associated access command (ACMD51) are
not
supported. If the host attempts to access this register in an I/O only card, a card in SPI mode shall respond
with an "Invalid Command" error response and a card in SD mode shall not respond.
4.10.7 SD
Status
There shall be a
maximum
of one SD Status register per SD card. If the card contains both memory and I/O, the
SD Status register information is unchanged from the SD 1.01 version and reflects the information from the
memory portion of the card. If the card is I/O only, the SD Status register and the associated access command
(ACMD13) are
not
supported. If the host attempts to access this register in an I/O only card, a card in SPI mode
shall respond with an "Invalid Command" error response and a card in SD mode shall not respond.
4.10.8 Card Status Register
The structure of the SDIO status register is shown in Table 4-7. For SDIO specific operations in the SD mode
that return the card status register contents (i.e. the response to CMD7), some bits are not applicable to I/O
operations and shall be returned as 0. These unused bits are identified as type N/A. For combo cards, the
values returned shall reflect the memory status. The CURRENT_STATE bits (12:9) shall reflect the memory
Controller State. For an I/O only card, the unused bits are 0 and the Current_State bits (12:9) shall be 0xF (15) to