Memory Card Specification Sheet

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SDIO Simplified Specification Version 2.00

5.2 IO_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.

5.2.1 CMD52 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

Index

110100b

Stuff Response Flags

Bit

7--------------------------0

Read or Write

Data

CRC7 E

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

’1’= error

The CRC check of the previous

command failed.

6 ILLEGAL_COMMAND E R ’0’= no error

’1’= error

Command not legal for the card

State.