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MMC/SD/SDIO Register Manual
Bits
Field Name
Description
Type
Reset
0x0:
Disable wakeup on card removal.
0x1:
Enable wakeup on card removal.
25
INS
Wake-up event enable on SD card insertion
RW
0
This bit enables wake-up events for card insertion assertion. Wakeup is
generated if the wake-up feature is enabled
(MMCi.
[2] ENAWAKEUP bit).
0x0:
Disable wakeup on card insertion.
0x1:
Enable wakeup on card insertion.
24
IWE
Wake-up event enable on SD card interrupt.
RW
0
This bit enables wake-up events for card interrupt assertion. Wakeup is
generated if the wake-up feature is enabled
(MMCi.
[2] ENAWAKEUP bit) and enable status bit
is set (MMCi.
[8] CIRQ_ENABLE bit).
0x0:
Disable wakeup on card interrupt
0x1:
Enable wakeup on card interrupt
23:20
Reserved
Reserved bit field. Do not write any value
R
0x0
19
IBG
Interrupt block at gap.
RW
0
This bit is valid only in 4-bit mode of SDIO card to enable interrupt
detection in the interrupt cycle at block gap for a multiple block transfer.
For MMC cards and for SD card this bit should be set to 0.
0x0:
Disable interrupt detection at the block gap in 4-bit mode
0x1:
Enable interrupt detection at the block gap in 4-bit mode
18
RWC
Read wait control.
RW
0
The read wait function is optional only for SDIO cards. If the card supports
read wait, this bit must be enabled, then requesting a stop at block gap
(MMCi.
[16] SBGR bit) generates a read wait period after
the current end of block. Be careful, if read wait is not supported it may
cause a conflict on mmci_dat line.
0x0:
Disable Read Wait Control. Suspend/Resume cannot be
supported.
0x1:
Enable Read Wait Control
17
CR
Continue request.
RW
0
This bit is used to restart a transaction that was stopped by requesting a
stop at block gap (MMCi.
[16] SBGR bit). Set this bit to 1
restarts the transfer. The bit is automatically set to 0 by the host controller
when transfer has restarted i.e. mmci_dat line is active
(MMCi.
[2] DLA bit) or transferring data
[8] WTA bit).
The Stop at block gap request must be disabled
(MMCi.
[16] SBGR bit =0) before setting this bit.
0x0:
No affect
0x1:
transfer restart
16
SBGR
Stop at block gap request.
RW
0
This bit is used to stop executing a transaction at the next block gap. The
transfer can restart with a continue request (MMCi.
[17] CR
bit) or during a suspend/resume sequence. In case of read transfer, the
card must support read wait control. In case of write transfer, the host
driver shall set this bit after all block data written. Until the transfer
completion (MMCi.
[1] TC bit set to 1), the host driver shall
leave this bit set to 1.If this bit is set, the local host shall not write to the
data register (MMCi.
0x0:
Transfer mode
0x1:
Stop at block gap
15:12
Reserved
Reserved bit field. Do not write any value.
R
0x0
11:9
SDVS
SD bus voltage select (All cards).
RW
0x0
The host driver should set these bits to select the voltage level for the card
according to the voltage supported by the system
(MMCi.
[26] VS18 bit, MMCi.
[25] VS30 bit,
[24] VS33 bit) before starting a transfer.
0x5:
1.8V (Typical)
3445
SWPU177N – December 2009 – Revised November 2010
MMC/SD/SDIO Card Interface
Copyright © 2009–2010, Texas Instruments Incorporated