MCI Bus Speed Mode

Specify the bus speed mode. More...

Macros
#define	ARM_MCI_BUS_DEFAULT_SPEED   (0x00)
	SD/MMC: Default Speed mode up to 25/26MHz.
#define	ARM_MCI_BUS_HIGH_SPEED   (0x01)
	SD/MMC: High Speed mode up to 50/52MHz.
#define	ARM_MCI_BUS_UHS_SDR12   (0x02)
	SD: SDR12 (Single Data Rate) up to 25MHz, 12.5MB/s: UHS-I (Ultra High Speed) 1.8V signaling.
#define	ARM_MCI_BUS_UHS_SDR25   (0x03)
	SD: SDR25 (Single Data Rate) up to 50MHz, 25 MB/s: UHS-I (Ultra High Speed) 1.8V signaling.
#define	ARM_MCI_BUS_UHS_SDR50   (0x04)
	SD: SDR50 (Single Data Rate) up to 100MHz, 50 MB/s: UHS-I (Ultra High Speed) 1.8V signaling.
#define	ARM_MCI_BUS_UHS_SDR104   (0x05)
	SD: SDR104 (Single Data Rate) up to 208MHz, 104 MB/s: UHS-I (Ultra High Speed) 1.8V signaling.
#define	ARM_MCI_BUS_UHS_DDR50   (0x06)
	SD: DDR50 (Dual Data Rate) up to 50MHz, 50 MB/s: UHS-I (Ultra High Speed) 1.8V signaling.

Description

Specify the bus speed mode.

The function ARM_MCI_Control with control = ARM_MCI_BUS_SPEED configures the bus speed of the MCI to the requested bits/s specified with arg.

The function ARM_MCI_Control with control = ARM_MCI_BUS_SPEED_MODE configures the bus speed mode of the MCI as specified with arg listed bellow.

The function ARM_MCI_GetCapabilities lists the supported bus speed modes. Initially, all SD cards use a 3.3 volt electrical interface. Some SD cards can switch to 1.8 volt operation. For example, the use of ultra-high-speed (UHS) SD cards requires 1.8 volt operation and a 4-bit bus data width. The data field uhs_signaling of the structure ARM_MCI_CAPABILITIES encodes whether the driver supports 1.8 volt UHS signaling.

See Also

• MCI Driver Strength

The following codes are defined:

Macro Definition Documentation

#define ARM_MCI_BUS_DEFAULT_SPEED   (0x00)

SD/MMC: Default Speed mode up to 25/26MHz.

#define ARM_MCI_BUS_HIGH_SPEED   (0x01)

SD/MMC: High Speed mode up to 50/52MHz.

#define ARM_MCI_BUS_UHS_SDR12   (0x02)

SD: SDR12 (Single Data Rate) up to 25MHz, 12.5MB/s: UHS-I (Ultra High Speed) 1.8V signaling.

#define ARM_MCI_BUS_UHS_SDR25   (0x03)

SD: SDR25 (Single Data Rate) up to 50MHz, 25 MB/s: UHS-I (Ultra High Speed) 1.8V signaling.

#define ARM_MCI_BUS_UHS_SDR50   (0x04)

SD: SDR50 (Single Data Rate) up to 100MHz, 50 MB/s: UHS-I (Ultra High Speed) 1.8V signaling.

#define ARM_MCI_BUS_UHS_SDR104   (0x05)

SD: SDR104 (Single Data Rate) up to 208MHz, 104 MB/s: UHS-I (Ultra High Speed) 1.8V signaling.

#define ARM_MCI_BUS_UHS_DDR50   (0x06)

SD: DDR50 (Dual Data Rate) up to 50MHz, 50 MB/s: UHS-I (Ultra High Speed) 1.8V signaling.