SDI Technologies SDIO Card manual Modified R6 Response, Reset for Sdio, Bus Width

SDIO Simplified Specification Version 2.00				©Copyright 2000-2007 SD Card Association
	SD Memory	SDIO		Comment
	Command	Command
	CMD18,		read/write commands.
	CMD24,
	CMD25

Table 4-1 Unsupported SD Memory Commands

4.3Modified 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

Direction

Command

New published RCA

[15:0] Card status

CRC7

end

bit

bit

index

[31:16] of the card

(see Table 4-3)

bit

(‘000011’)

Table 4-2 R6 response to CMD3

Bits

Identifier

Type

Value

Description

Clear

Condition

15

COM_CRC_ERROR

E R

’0’= no error

The CRC check of the previous

B

’1’= error

command failed

14

ILLEGAL_COMMAND

E R

’0’= no error

Command not legal for the card

B

’1’= error

state

13

ERROR

E R X

’0’= no error

A general or an unknown error

C

’1’= error

occurred during the operation

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

4.4Reset 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.

4.5Bus 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.

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