SDI Technologies SDIO Card manual Byte Count Values, 1 CMD53 Data Transfer Format

©Copyright 2000-2007 SD Card Association

SDIO Simplified Specification Version 2.00

address that increment by 1 after each operation. This command is used when large amounts of I/O data exist within the I/O card in a RAM like data buffer. In this operation, the start address is loaded into the Register Address field. The first operation occurs at that address within the I/O card. The next operation shall occur at address+1 with the address incrementing by 1 until the operation has completed. As with OP Code 0, the number of bytes is set in the Byte Count field of the command.

Register Address:	Start Address of I/O register to read or write. Range is [0x1FFFF:0]
Byte/Block Count	If the command is operating on bytes (Block Mode = 0), this field contains the
	number of bytes to read or write. A value of 0x000 shall cause 512 bytes to be read
	or written.
	Count Value	0x000	0x001	0x002 ----	0x1FF
	Bytes Transferred	512	1	2	511
	Block Transferred	∞	1	2	511
	Table 5-3 Byte Count Values
	If the command is in block mode (Block Mode=1), the Block Count field specifies the
	number of Data Blocks to be transferred following this command. A value of 0x000
	indicates that the count set to infinite. In this case, the I/O blocks shall be transferred
	until the operation is aborted by writing to the I/O abort function select bits (ASx) in
	the CCCR (see Table 6-1 and Table 6-2). Table 5-3 shows the relationship between
	the value in the command and the actual number of bytes transferred.
CRC7:	7 bits of CRC data
E(nd bit):	End bit, always 1

The response from the SDIO card to CMD53 shall be R5 (the same as CMD52) as defined in 5.2. For CMD53, the 8-bit data field shall be stuff bits and shall be read as 0x00. Also, the ERROR response bit shall be type “E R X” (see Table 5-1).

5.3.1CMD53 Data Transfer Format

When executing the IO_RW_EXTENDED (CMD53), the multi-byte or multi-block data transfer is similar to the data transfer for memory. For the multi-byte transfer modes (block mode=0) the following applies:

IO_RW_EXTENDED byte read is similar to CMD17 (READ_SINGLE_BLOCK)

IO_RW_EXTENDED byte write is similar to CMD24 (WRITE_BLOCK)

Note that the byte count for this transfer is set in the command, rather than the fixed block size. Thus, the size of the data payload is in the range of 1-512 bytes. The block mode is similar to the following memory commands:

IO_RW_EXTENDED block read is similar to CMD18 (READ_MULTIPLE_BLOCK)

IO_RW_EXTENDED block write is similar to CMD25 (WRITE_MULTIPLE_BLOCK)

For the block mode the only difference is that for a fixed block count, the host does not need to stop the transfer, as it continues until the block count is satisfied. If the block count is set to zero, the operation is identical to the memory mode in that the host must stop the transfer.

5.3.2Special Timing for CMD53 Multi-Block Read This section is not included in the Simplified Specification.

25