Specifications

©Copyright 2001-2013 SD Group (Panasonic, SanDisk, Toshiba) and SD Card Association
Physical Layer Simplified Specification Version 4.10
155
Figure 7-2: SPI Mode Initialization Flow
READ_OCR (CMD58) is designed to provide SD Memory Card hosts with a mechanism to identify
cards that do not match the V
DD
range desired by the host. If the host does not accept voltage range, it
shall not proceed with further initialization sequence. The levels in the OCR register shall be defined
accordingly (See Chapter 5.1).
SD_SEND_OP_COND (ACMD41) is used to start initialization and to check if the card has completed
initialization. It is mandatory to issue CMD8 prior to the first ACMD41. Receiving of CMD8 expands the
CMD58 and ACMD41 function; HCS (High Capacity Support) in the argument of ACMD41 and CCS
(Card Capacity Status) in the response of CMD58. HCS is ignored by the card, which didn't accept
CMD8. Standard Capacity SD Memory Card ignores HCS. The "in idle state" bit in the R1 response of
ACMD41 is used by the card to inform the host if initialization of ACMD41 is completed. Setting this bit
to "1" indicates that the card is still initializing. Setting this bit to "0" indicates completion of initialization.
The host repeatedly issues ACMD41 until this bit is set to "0". The card checks the HCS bit in the OCR
only at the first ACMD41. While repeating ACMD41, the host shall not issue another command except
CMD0.
After initialization is completed, the host should get CCS information in the response of CMD58. CCS is
valid when the card accepted CMD8 and after the completion of initialization. CCS=0 means that the
card is SDSD. CCS=1 means that the card is SDHC or SDXC.
Illegal Command
Compatible voltage range
and check pattern is correct
Cards with non compatible voltage range
Cards with non
compatible voltage
range
Card returns
'in_
idle_
state
'=
1
Card returns
'
in_idle
_state=0
'
Card returns
'
in_idle_
state'=
0
Ver2.
00 or later
CCS=0
CCS=
1
Illegal Command
If host supports
SDHC or SDXC,
HCS is set to 1
ACMD41
(
argument=
0
x0
)
CMD8
ACMD
41
with HCS=0
or1
Valid
Response?
Card with compatible
Voltage range
Card is
ready?
Card is
ready?
Unusable
Card
Unusable
Card
Unusable
Card
Ver1.
X
Standard Capacity
SD Memory Card
CCS in
Response?
Ver
2.00 or later
Standard Capacity
SD Memory Card
Ver2.
00 or later
High Capacity or
Extended Capacity
SD Memory Card
Not SD Memory Card
CMD58
(
READ OCR
)
Not Mandatory to send CMD58
:
Though it is recommended
to be done in order to get
the supported voltage range
of the card
.
CMD
58
(
READ OCR)
CMD
58
(
Get CCS)
CMD0
+
CS Asserted("0")
Card returns response
without illegal command
Ver
2.
00
or later
SD Memory Card
Ver1
.
X SD Memory Card
or Not SD Memory Card
Non-
compatible voltage range
or check pattern error
Card returns
'in_
idle_state
'=1
Power
-
on