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Registers

4.1MMC Control Register (MMCCTL)

The MMC control register (MMCCTL) is used to enable or configure various modes of the MMC controller. Set or clear the DATRST and CMDRST bits at the same time to reset or enable the MMC controller.

The MMC control register (MMCCTL) is shown in Figure 18 and described in Table 6.

Figure 18. MMC Control Register (MMCCTL)

31

 

 

 

 

 

16

 

 

Reserved

 

 

 

 

 

 

R-0

 

 

 

 

15

 

 

11

10

9

8

 

 

Reserved

 

PERMDX

PERMDR

Reserved

 

 

R-0

 

R/W-0

R/W-0

R-0

7

6

5

3

2

1

0

 

DATEG

Reserved

 

WIDTH

CMDRST

DATRST

 

R/W-0

R-0

 

R/W-0

R/W-0

R/W-0

LEGEND: R/W = Read/Write; R = Read only; -n= value after reset

 

 

 

 

 

 

 

Table 6. MMC Control Register (MMCCTL) Field Descriptions

Bit

Field

Value

Description

31-11

Reserved

0

Reserved

10

PERMDX

 

Endian select when writing.

 

 

0

Little endian is selected.

 

 

1

Big endian is selected.

9

PERMDR

 

Endian select when reading.

 

 

0

Little endian is selected.

 

 

1

Big endian is selected.

8

Reserved

0

Reserved

7-6

DATEG

0-3h

DAT3 edge detection select.

 

 

0

DAT3 edge detection is disabled.

 

 

1h

DAT3 rising-edge detection is enabled.

 

 

2h

DAT3 falling-edge detection is enabled.

 

 

3h

DAT3 rising-edge and falling-edge detections are enabled.

5-3

Reserved

0

Reserved

2

WIDTH

 

Data bus width (MMC mode only).

 

 

0

Data bus has 1 bit (only DAT0 is used).

 

 

1

Data bus has 4 bits (all DAT0-3 are used).

1

CMDRST

 

CMD logic reset.

 

 

0

CMD line portion is enabled.

 

 

1

CMD line portion is disabled and in reset state.

0

DATRST

 

DAT logic reset.

 

 

0

DAT line portion is enabled.

 

 

1

DAT line portion is disabled and in reset state.

SPRUE30B –September 2006

Multimedia Card (MMC)/Secure Digital (SD) Card Controller

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Texas Instruments TMS320DM644x manual MMC Control Register Mmcctl Field Descriptions, Bit Field Value Description