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ATSAM4S-XPLD
822
SAM4S [DATASHEET]
11100E–ATARM–24-Jul-13
37.9
SD/SDIO Card Operation
The High Speed MultiMedia Card Interface allows processing of SD Memory (Secure Digital Memory Card) and SDIO
(SD Input Output) Card commands.
(SD Input Output) Card commands.
SD/SDIO cards are based on the MultiMedia Card (MMC) format, but are physically slightly thicker and feature higher
data transfer rates, a lock switch on the side to prevent accidental overwriting and security features. The physical form
factor, pin assignment and data transfer protocol are forward-compatible with the High Speed MultiMedia Card with some
additions. SD slots can actually be used for more than flash memory cards. Devices that support SDIO can use small
devices designed for the SD form factor, such as GPS receivers, Wi-Fi or Bluetooth adapters, modems, barcode readers,
IrDA adapters, FM radio tuners, RFID readers, digital cameras and more.
data transfer rates, a lock switch on the side to prevent accidental overwriting and security features. The physical form
factor, pin assignment and data transfer protocol are forward-compatible with the High Speed MultiMedia Card with some
additions. SD slots can actually be used for more than flash memory cards. Devices that support SDIO can use small
devices designed for the SD form factor, such as GPS receivers, Wi-Fi or Bluetooth adapters, modems, barcode readers,
IrDA adapters, FM radio tuners, RFID readers, digital cameras and more.
SD/SDIO is covered by numerous patents and trademarks, and licensing is only available through the Secure Digital
Card Association.
Card Association.
The SD/SDIO Card communication is based on a 9-pin interface (Clock, Command, 4 x Data and 3 x Power lines). The
communication protocol is defined as a part of this specification. The main difference between the SD/SDIO Card and the
High Speed MultiMedia Card is the initialization process.
communication protocol is defined as a part of this specification. The main difference between the SD/SDIO Card and the
High Speed MultiMedia Card is the initialization process.
The SD/SDIO Card Register (HSMCI_SDCR) allows selection of the Card Slot and the data bus width.
The SD/SDIO Card bus allows dynamic configuration of the number of data lines. After power up, by default, the
SD/SDIO Card uses only DAT0 for data transfer. After initialization, the host can change the bus width (number of active
data lines).
SD/SDIO Card uses only DAT0 for data transfer. After initialization, the host can change the bus width (number of active
data lines).
37.9.1 SDIO Data Transfer Type
SDIO cards may transfer data in either a multi-byte (1 to 512 bytes) or an optional block format (1 to 511 blocks), while
the SD memory cards are fixed in the block transfer mode. The TRTYP field in the HSMCI Command Register
(HSMCI_CMDR) allows to choose between SDIO Byte or SDIO Block transfer.
the SD memory cards are fixed in the block transfer mode. The TRTYP field in the HSMCI Command Register
(HSMCI_CMDR) allows to choose between SDIO Byte or SDIO Block transfer.
The number of bytes/blocks to transfer is set through the BCNT field in the HSMCI Block Register (HSMCI_BLKR). In
SDIO Block mode, the field BLKLEN must be set to the data block size while this field is not used in SDIO Byte mode.
SDIO Block mode, the field BLKLEN must be set to the data block size while this field is not used in SDIO Byte mode.
An SDIO Card can have multiple I/O or combined I/O and memory (called Combo Card). Within a multi-function SDIO or
a Combo card, there are multiple devices (I/O and memory) that share access to the SD bus. In order to allow the sharing
of access to the host among multiple devices, SDIO and combo cards can implement the optional concept of
suspend/resume (Refer to the SDIO Specification for more details). To send a suspend or a resume command, the host
must set the SDIO Special Command field (IOSPCMD) in the HSMCI Command Register.
a Combo card, there are multiple devices (I/O and memory) that share access to the SD bus. In order to allow the sharing
of access to the host among multiple devices, SDIO and combo cards can implement the optional concept of
suspend/resume (Refer to the SDIO Specification for more details). To send a suspend or a resume command, the host
must set the SDIO Special Command field (IOSPCMD) in the HSMCI Command Register.
37.9.2 SDIO Interrupts
Each function within an SDIO or Combo card may implement interrupts (Refer to the SDIO Specification for more
details). In order to allow the SDIO card to interrupt the host, an interrupt function is added to a pin on the DAT[1] line to
signal the card’s interrupt to the host. An SDIO interrupt on each slot can be enabled through the HSMCI Interrupt Enable
Register. The SDIO interrupt is sampled regardless of the currently selected slot.
details). In order to allow the SDIO card to interrupt the host, an interrupt function is added to a pin on the DAT[1] line to
signal the card’s interrupt to the host. An SDIO interrupt on each slot can be enabled through the HSMCI Interrupt Enable
Register. The SDIO interrupt is sampled regardless of the currently selected slot.
37.10 CE-ATA Operation
CE-ATA maps the streamlined ATA command set onto the MMC interface. The ATA task file is mapped onto MMC
register space.
register space.
CE-ATA utilizes five MMC commands:
GO_IDLE_STATE (CMD0): used for hard reset.
STOP_TRANSMISSION (CMD12): causes the ATA command currently executing to be aborted.
FAST_IO (CMD39): Used for single register access to the ATA taskfile registers, 8 bit access only.
RW_MULTIPLE_REGISTERS (CMD60): used to issue an ATA command or to access the control/status registers.
RW_MULTIPLE_BLOCK (CMD61): used to transfer data for an ATA command.
CE-ATA utilizes the same MMC command sequences for initialization as traditional MMC devices.