Chapter 4 – SD Card Protocol Description
Revision 2.2
SanDisk SD Card Product Manual
© 2004 SanDisk Corporation
4-5
12/08/04
Figure 4-7
SD Memory Card State Diagram—Card Identification Mode
4.3.1 Reset
The GO_IDLE_STATE (CMD0) is the software-reset command that makes each SD Card
move into an idle state regardless of the card’s current state. Cards already in an inactive
state are not affected by this command.
After power-on by the host, all cards are in an idle state, including cards that were in an
inactive state.
1
After power-on or CMD0, all card CMD lines are in input mode, waiting for the start-bit of
the next command. The cards are initialized with a default relative card address
(RCA=0x0000) and a default driver-stage-register setting (lowest speed, highest driving
current capability).
4.3.2
Operating Voltage Range Validation
The physical specification standard, defined by the SDA, requires that all SD cards can use
any operating voltage between V
DD
-min and V
DD
-max to establish communication with the
host. However, during data transfer, minimum and maximum values for V
DD
are defined in
the Operations Condition Register (OCR) and may not cover the entire range. Card hosts
are expected to read the CSD Register and select proper V
DD
values or reject the card.
An SD Card that stores the CID and CSD data in the payload memory can communicate
this information under data-transfer V
DD
conditions only. In other words, if the host and
1
At least 74 clock cycles are required prior to starting bus communication.
Idle State (idle)
ACMD41
Ready State
(ready)
CMD2
Identification State
(ident)
CMD3
Standby State
(stby)
CMD3
Inactive State (ina)
CMD15
CMD0
CMD0
CS Asserted (0)
SPI Operation
Mode
From all states
except "ina"
Card responds
w/new RCA
From all states in
Data Transfer
Mode
Card responds
w/new RCA
Start MMC
initialization process
starting at CMD1
No response (non
valid command)
must be an MMC
Card is busy or
host omitted
voltage range
Cards w/non-compatible voltage range
Card Identification Mode
Data Transfer Mode
Power On