SDI Technologies SDIO Card User Manual
©Copyright 2000-2007 SD Card Association
SDIO Simplified Specification Version 2.00
16
SD Memory
Command
SDIO
Command
Comment
CMD18,
CMD24,
CMD25
CMD24,
CMD25
read/write commands.
Table 4-1 Unsupported SD Memory Commands
4.3
Modified R6 Response
The normal response to CMD3 by a memory card is R6 as shown in Table 4-2. The card status bits (23-8) are
changed when CMD3 is sent to an I/O only card. In this case, the 16 bits of response shall be the SDIO-only
values shown in Table 4-3
Bit position
47
46
[45:40]
[39:8] Argument field
[7:1]
0
Width
(bits)
1
1
6 16
16 7
1
Value
‘0’
‘0’
X X
X X
‘1’
Description Start
bit
Direction
bit
Command
index
(‘000011’)
New published RCA
[31:16] of the card
[15:0] Card status
(see
Table 4-3)
CRC7
end
bit
Table 4-2 R6 response to CMD3
Bits
Identifier
Type
Value
Description
Clear
Condition
15
COM_CRC_ERROR
E R
’0’= no error
’1’= error
’1’= error
The CRC check of the previous
command failed
command failed
B
14
ILLEGAL_COMMAND
E R
’0’= no error
’1’= error
’1’= error
Command not legal for the card
state
state
B
13
ERROR
E R X ’0’= no error
’1’= error
A general or an unknown error
occurred during the operation
occurred during the operation
C
12: 0
Undefined. Should read as 0 for SDIO only cards. Host should ignore these bits.
Note: Please refer to sections 7.3.4 of the SD Physical Specification for explanation of the entries in the Type
and Clear Condition columns.
Table 4-3 SDIO R6 Status Bits
4.4
Reset for SDIO
In order to reset all functions within an SDIO card or the SDIO portion of a combo card, a method different than
that used for SD memory is defined. The reset command (CMD0) is only used for memory or the memory
portion of Combo cards. In order to reset an I/O only card or the I/O portion of a combo card, use CMD52 to write
a 1 to the RES bit in the CCCR (bit 3 of register 6). Note that in the SD mode, CMD0 is only used to indicate
entry into SPI mode and shall be supported. An I/O only card or the I/O portion of a combo card is not reset by
CMD0.
4.5 Bus
Width
For a SD memory card, the bus width for SD mode is set using ACMD6. The SDIO card uses a write to the
CCCR using CMD52 to select bus width. In the case of a combo card, both selection methods exist. In this case,
the host shall set the bus width in both locations by issuing both the ACMD6 and the CCCR write using CMD52
with the same width before starting any data transfers. For details on changing the bus for an SDIO card, see
Table 6-2. . For a Combo Card, changing bus width is handled as shown in Table 4-4.