Multimedia Card Registers
Table 18-36. SD_HCTL Register Field Descriptions (continued)
Bit
Field
Type
Reset
Description
8
SDBP
R/W
0h
SD bus power.
Before setting this bit, the host driver shall select the SD bus voltage
(SD_HCTL
[11:9] SDVS bits).
If the host controller detects the No card state, this bit is
automatically cleared to 0.
If the module is power off, a write in the command register
(SD_CMD) will not start the transfer.
A write to this bit has no effect if the selected SD bus voltage is not
supported according to capability register (SD_CAPA[VS*]).
0x0 = Power off
0x1 = Power on
7
CDSS
R/W
0h
Card Detect Signal Selection.
This bit selects source for the card detection.
When the source for the card detection is switched, the interrupt
should be disabled during the switching period by clearing the
Interrupt Status/Signal Enable register in order to mask unexpected
interrupt being caused by the glitch.
The Interrupt Status/Signal Enable should be disabled during over
the period of debouncing.
0x0 = SDCD# is selected (for normal use).
0x1 = The Card Detect Test Level is selected (for test purposes).
6
CDTL
R/W
0h
Card Detect Test Level.
This bit is enabled while the Card Detect Signal Selection is set to 1
and it indicates card inserted or not.
0 = No card
1 = Card inserted.
5
Reserved
R
0h
4-3
DMAS
R/W
0h
DMA Select.
One of the supported DMA modes can be selected.
The host driver shall check support of DMA modes by referencing
the Capabilities register.
Use of selected DMA is determined by DMA Enable of the Transfer
Mode register.
This register is only meaningful when MADMA_EN is set to 1.
When MADMA_EN is cleared to 0 the bit field is read only and
returned value is 0.
0x0 = Reserved
0x1 = Reserved
0x2 = 32-bit Address ADMA2 is selected.
0x3 = Reserved
2
HSPE
R/W
0h
High Speed Enable.
Before setting this bit, the Host Driver shall check the High Speed
Support in the Capabilities register.
If this bit is cleared to 0 (default), the Host Controller outputs CMD
line and DAT lines at the falling edge of the SD Clock.
If this bit is set to 1, the Host Controller outputs CMD line and DAT
lines at the rising edge of the SD Clock.
This bit shall not be set when dual data rate mode is activated in
SD_CON[DDR].
0x0 = Normal speed mode
0x1 = High speed mode
1
DTW
R/W
0h
Data transfer width.
This bit must be set following a valid SET_BUS_WIDTH command
(ACMD6) with the value written in bit 1 of the argument.
Prior to this command, the SD card configuration register (SCR)
must be verified for the supported bus width by the SD card.
0x0 = 1-bit Data width (mmc_dat0 used)
0x1 = 4-bit Data width (mmc_dat[3:0] used)
0
Reserved
R
0h
3421
SPRUH73H – October 2011 – Revised April 2013
Multimedia Card (MMC)
Copyright © 2011–2013, Texas Instruments Incorporated