RM0033 Rev 9 761/1381
RM0033 Secure digital input/output interface (SDIO)
791
26.4.12 SD status register
The SD status contains status bits that are related to the SD memory card proprietary
features and may be used for future application-specific usage. The size of the SD Status is
one data block of 512 bits. The contents of this register are transmitted to the SDIO card
host if ACMD13 is sent (CMD55 followed with CMD13). ACMD13 can be sent to a card in
transfer state only (card is selected).
Table 112 defines the different entries of the SD status register. The type and clear condition
fields in the table are abbreviated as follows:
Type:
• E: error bit
• S: status bit
• R: detected and set for the actual command response
• X: detected and set during command execution. The SDIO card Host must poll the card
by issuing the status command to read these bits
12:9 CURRENT_STATE S R
0 = Idle
1 = Ready
2 = Ident
3 = Stby
4 = Tran
5 = Data
6 = Rcv
7 = Prg
8 = Dis
9 = Btst
10-15 = reserved
The state of the card when receiving the
command. If the command execution
causes a state change, it will be visible to
the host in the response on the next
command. The four bits are interpreted as
a binary number between 0 and 15.
B
8 READY_FOR_DATA S R
’0’= not ready ‘1’
= ready
Corresponds to buffer empty signalling on
the bus
-
7 SWITCH_ERROR E X
’0’= no error
’1’= switch error
If set, the card did not switch to the
expected mode as requested by the
SWITCH command
B
6 Reserved
5 APP_CMD S R
‘0’ = Disabled
‘1’ = Enabled
The card will expect ACMD, or an
indication that the command has been
interpreted as ACMD
C
4 Reserved for SD I/O Card
3 AKE_SEQ_ERROR E R
’0’= no error
’1’= error
Error in the sequence of the
authentication process
C
2 Reserved for application specific commands
1
Reserved for manufacturer test mode
0
Table 111. Card status (continued)
Bits Identifier Type Value Description
Clear
condition
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