GD32W51x User Manual
773
Table 23-5. Block-Oriented read commands (class 2)
Cm d
index
type
argum ent
Response
form at
Abbreviation
Description
CMD16
ac
[31:0] block
length
R1
SET_BLOCKLEN
In the case of a Standard
Capacity SD and MMC, this
command sets the block length
(in bytes) for all follow ing block
commands (read, w rite, lock).
Default is 512 Bytes. Set length
is valid for memory access
commands only if partial block
read operation are allow ed in
CSD.
In the case of a High Capacity
SD Memory Card, block length
set by CMD16 command does
not affect the memory read and
w rite commands. Alw ays 512
Bytes fixed block length is used.
In both cases, if block length is
set larger than 512Bytes, the
card sets the
BLOCK_LEN_ERROR bit.
CMD17
adtc
[31:0] data
address
R1
READ_SINGLE_B
LOCK
In the case of a Standard
Capacity SD and MMC, this
command reads a block of the
size selected by the
SET_BLOCKLEN command.
In the case of a High Capacity
Card, block length is fixed 512
Bytes regardless of the
SET_BLOCKLEN command.
CMD18
adtc
[31:0] data
address
R1
READ_MULTIPLE
_BLOCK
Continuously transfers data
blocks from card to host until
interrupted by a
STOP_TRA NSMISSION
command. Block length is
specified the same as
READ_SINGLE_BLOCK
command.
Note:
The transferred data must not cross a physical block boundary, unless
READ_BLK_MISALIGN is set in the CSD register