©Copyright 2000-2007 SD Card Association

SDIO Simplified Specification Version 2.00

5.2IO_RW_DIRECT Response (R5)

The SDIO card’s response to CMD52 shall be in one of two formats. If the communication between the card and host is in the 1-bit or 4-bit SD mode, the response shall be in a 48-bit response (R5) as described in 5.2.1. If the communication is using the SPI mode, the response shall be a 16-bit R5 response as described in 5.2.2.

5.2.1CMD52 Response (SD modes)

The SDIO card’s response to CMD52 in the SD mode is shown in Figure 5-2. If the operation was a read command, the data being read is returned as an 8-bit value. In addition, 15 bits of status information is returned. The format of the SD response is as follows:

S

D

Command

Stuff

Response Flags

 

Read or Write

CRC7

E

 

 

Index

 

Bit

 

Data

 

 

 

 

110100b

 

7--------------------------

0

 

 

 

1

1

6

16

8

 

8

7

1

Figure 5-2 R5 IO_RW_DIRECT Response (SD modes)

The IO_RW_DIRECT response (R5) contains the following fields:

S(tart bit):

Start bit. Always 0

 

 

 

D(irection):

Direction. 0 indicates transfer card to host (Response)

 

 

Command Index:

Identifies the “IO_RW_DIRECT” command with a value of 110100b

 

 

Stuff Bits

 

Not used, shall be set to 0

 

 

 

Response Flags

8 Bits of flag data indicating the status of the SDIO card. Table 5-1 shows the format

 

 

 

 

of these flag bits.

 

 

 

 

Read or Write Data:

For an I/O write (R/W=1) with the RAW Flag set (RAW=1) this field shall contain the

 

 

 

 

value read from the addressed register after the write of the data contained in the

 

 

 

 

command. Note that in this case, the read-back data may not be the same as the

 

 

 

 

data written to the register, depending on the design of the hardware. For an I/O

 

 

 

 

write with the RAW bit=0, the SDIO function shall not do a read after write operation,

 

 

 

 

and the data in this field shall be identical to the data byte in the write command. For

 

 

 

 

an I/O read (R/W=0), the actual value read from that I/O location is returned in this

 

 

 

 

field.

 

 

 

 

 

 

CRC7:

 

7 bits of CRC data

 

 

 

E(nd bit):

 

End bit, always 1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bits

 

Identifier

 

Type

 

Value

Description

Clear

 

 

 

 

 

 

 

 

 

 

Condition

 

 

7

 

COM_CRC_ERROR

E R

 

’0’= no error

The CRC check of the previous

B

 

 

 

 

 

 

 

 

’1’= error

command failed.

 

 

 

6

 

ILLEGAL_COMMAND

E R

 

’0’= no error

Command not legal for the card

B

 

 

 

 

 

 

 

 

’1’= error

State.

 

 

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SDI Technologies SDIO Card manual Iorwdirect Response R5, 1 CMD52 Response SD modes, Identifier Type Value Description