Secure Digital (SD) Card Protocol Description
4-6
SanDisk Secure Digital (SD) Card Product Manual, Rev. 1.9 © 2003 SANDISK CORPORATION
Power On
Card is Busy
or Host ommitted
voltage range
Idle State
(idle)
ACMD41
Ready State
(ready)
CMD2
Identification
State (ident)
CMD3
Stand-by
State (stby)
CMD0
From all states except (ina)
Inactive State
(ina)
CMD15
Cards with non-compatible
voltage range
Card responds
with new RCA
Card Identification Mode
Data Transfer Mode
From all States in Data
Transfer Mode
CMD3
Card responds
with new RCA
No response
(non-valid command)
Must be an MMC
Start MMC
initialization process
starting at CMD1
SPI Operation
Mode
CMD0
CS Asserted ("0")
Figure 4-7. SD Card State Diagram (Card Identification Mode)
4.3.1. Reset
GO_IDLE_STATE (CMD0) is the software reset command and sets each SD Card to Idle State regardless of the
current card state. SD Cards in Inactive State are not affected by this command.
After power-on by the host, all SD Cards are in Idle State, including the cards that were in Inactive State. Note that
at least 74 clock cycles are required prior to starting bus communication.
After power-on or CMD0, all SD Cards’ 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 with a default driver
stage register setting (lowest speed, highest driving current capability).
