DocID018909 Rev 11
RM0090
Secure digital input/output interface (SDIO)
1067
31.9.4 SDIO
command
register (SDIO_CMD)
Address offset: 0x0C
Reset value: 0x0000 0000
The SDIO_CMD register contains the command index and command type bits. The
command index is sent to a card as part of a command message. The command type bits
control the command path state machine (CPSM).
Note:
After a data write, data cannot be written to this register for three SDIOCLK (48 MHz) clock
periods plus two PCLK2 clock periods.
MultiMediaCards can send two kinds of response: short responses, 48 bits long, or long
responses,136 bits long. SD card and SD I/O card can send only short responses, the
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
Reserved
CE
-A
TA
CMD
nI
EN
ENCMDc
om
pl
SDI
O
S
u
spend
CPSME
N
WA
IT
P
E
N
D
WA
IT
IN
T
W
A
IT
RESP
CMDINDEX
rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw
Bits 31:15 Reserved, must be kept at reset value
Bit 14
ATACMD:
CE-ATA command
If ATACMD is set, the CPSM transfers CMD61.
Bit 13
nIEN:
not Interrupt Enable
if this bit is 0, interrupts in the CE-ATA device are enabled.
Bit 12
ENCMDcompl:
Enable CMD completion
If this bit is set, the command completion signal is enabled.
Bit 11
SDIOSuspend:
SD I/O suspend command
If this bit is set, the command to be sent is a suspend command (to be used only with SDIO
card).
Bit 10
CPSMEN:
Command path state machine (CPSM) Enable bit
If this bit is set, the CPSM is enabled.
Bit 9
WAITPEND:
CPSM Waits for ends of data transfer (CmdPend internal signal).
If this bit is set, the CPSM waits for the end of data transfer before it starts sending a
command.
Bit 8
WAITINT:
CPSM waits for interrupt request
If this bit is set, the CPSM disables command timeout and waits for an interrupt request.
Bits 7:6
WAITRESP
: Wait for response bits
They are used to configure whether the CPSM is to wait for a response, and if yes, which
kind of response.
00: No response, expect CMDSENT flag
01: Short response, expect CMDREND or CCRCFAIL flag
10: No response, expect CMDSENT flag
11: Long response, expect CMDREND or CCRCFAIL flag
Bits 5:0
CMDINDEX:
Command index
The command index is sent to the card as part of a command message.