Secure Digital (SD) Card Protocol Description
SanDisk Secure Digital (SD) Card Product Manual, Rev. 1.9 © 2003 SANDISK CORPORATION
4-31
<---- Host Command ---->
< N
cr
Cycles >
<----- Card response----->
<Host Cmnd>
CMD
S T
content
CRC E Z Z P
P * * * * * * P
S T
content
CRC E
S T
Content
--Data block->
CRC Status
1
Å
------------Card is programming ----------
Æ
DAT
D D D D D Z Z S Status E Z Z S L
* * * * * * ** * * * * * * * * * * * *
E Z Z Z Z Z Z Z Z
1) The card CRC status response was interrupted by the host.
Figure 4-22. Stop Transmission During CRC Status Transfer from the Card
All previous examples dealt with the scenario of the host stopping the data transmission during an active data
transfer. The following two diagrams describe a scenario of receiving the stop transmission between data blocks. In
the first example the card is busy programming the last block while in the second the card is idle. However, there
are still unprogrammed data blocks in the input buffers. These blocks are being programmed as soon as the stop
transmission command is received and the card activates the busy signal.
<---- Host Command ---->
< N
cr
Cycles >
<----- Card response----->
<Host Cmnd>
CMD S T content CRC E Z Z P * * * P S T
content
CRC E S T Content
<----------
Card
is
programming
---------->
DAT
S L
* * * * * * * * * * * * * * * * * * * * * * * ** ** * * * * * * * * *
L E Z Z Z Z Z Z Z Z
Figure 4-23. Stop Transmission Received After Last Data Block. Card is Busy Programming
<---- Host Command ---->
< N
cr
Cycles >
<----- Card response----->
<Host Cmnd>
CMD S T content CRC E Z Z P * * * P S T
content
CRC E S T Content
<---------- Card is programming ---------->
DAT
Z Z Z Z Z Z Z Z Z Z Z S L
* ************************* *
L E Z Z Z Z Z Z Z Z
Figure 4-24. Stop Transmission Received After Last Data Block. Card becomes Busy
Erase, Set and Clear Write Protect Timing
The host must first tag the start (CMD32) and end (CMD33) addresses of the range to be erased. The erase
command (CMD38), once issued, will erase all the selected write blocks. Similarly, set and clear write protect
commands start a programming operation as well. The card will signal “busy” (by pulling the DAT line low) for the
duration of the erase or programming operation. The bus transaction timings are the same as given for stop tran
command in Figure 4-23.
Reselecting a Busy Card
When a busy card, which is currently in the dis state, is reselected it will reinstate its busy signaling on the data line.
The timing diagram for this command/response/busy transaction is the same as given for stop tran command in
Figure 4-24.