UDMA SD Card Interface

Features

Theory of Operation

Programming Model

UDMA SDIO Card CSRs

RX_SADDR offset = 0x00

Field	Bits	Type	Default	Description
SADDR	31:0	RW		Address of receive memory buffer:
				Read: value of pointer until transfer is over, then 0
				Write: set memory buffer start address

RX_SIZE offset = 0x04

Field	Bits	Type	Default	Description
SIZE	15:0	RW		Buffer size in bytes (1MB max)
				Read: bytes remaining until transfer complete
				Write: set number of bytes to transfer

RX_CFG offset = 0x08

Field	Bits	Type	Default	Description
CLR	5:5	WO		Clear the receive channel
PENDING	5:5	RO		Receive transaction is pending
EN	4:4	RW		Enable the receive channel
DATASIZE	2:1	RW	0x02	Controls uDMA address increment
				0x00: increment address by 1 (data is 8 bits)
				0x01: increment address by 2 (data is 16 bits)
				0x02: increment address by 4 (data is 32 bits)
				0x03: increment address by 0
CONTINUOUS	0:0	RW		0x0: stop after last transfer for channel
				0x1: after last transfer for channel,
				reload buffer size and start address and restart channel

TX_SADDR offset = 0x10

Field	Bits	Type	Default	Description
SADDR	11:0	RW		Address of transmit memory buffer:
				Read: value of pointer until transfer is over, then 0

TX_SIZE offset = 0x14

Field	Bits	Type	Default	Description
SIZE	15:0	RW		Buffer size in bytes (1MB max)

TX_CFG offset = 0x18

Field	Bits	Type	Default	Description
CLR	5:5	WO		Clear the transmit channel
PENDING	5:5	RO		Transmit transaction is pending
EN	4:4	RW		Enable the transmit channel
DATASIZE	2:1	WO	0x02	Controls uDMA address increment (Reads as 0x00)
				0x00: increment address by 1 (data is 8 bits)
				0x01: increment address by 2 (data is 16 bits)
				0x02: increment address by 4 (data is 32 bits)
				0x03: increment address by 0
CONTINUOUS	0:0	RW		0x0: stop after last transfer for channel
				0x1: after last transfer for channel,
				reload buffer size and start address and restart channel

CMD_OP offset = 0x20

Field	Bits	Type	Default	Description
CMD_OP	13:8	WO		SDIO command opcode
CMD_RSP_TYPE	2:0	WO		Response type:
				0x0: No response
				0x1: 48 bits with CRC
				0x2: 48 bits with no CRC
				0x3: 136 bits
				0x4: 48 bits with BUSY check

CMD_ARG offset = 0x24

Field	Bits	Type	Default	Description
CMD_ARG	31:0	WO		Argument to be sent with the command

DATA_SETUP offset = 0x28

Field	Bits	Type	Default	Description
BLOCK_SIZE	25:16	W		Block size
BLOCK_NUM	15:8	W		Number of blocks
DATA_QUAD	2:2	W		Use QUAD mode
DATA_RWN	1:1	W		Set transfer direction:
				0x0: write
				0x1: read
DATA_EN	0:0	W		Enable data transfer for current command

START offset = 0x2C

Field	Bits	Type	Default	Description
START	0:0	W		Start SDIO transfer

RSP0 offset = 0x30

Field	Bits	Type	Default	Description
RSP0	31:0	R		Bytes[3:0] of the response

RSP1 offset = 0x34

Field	Bits	Type	Default	Description
RSP1	31:0	R		Bytes[7:4] of the response

RSP2 offset = 0x38

Field	Bits	Type	Default	Description
RSP2	31:0	R		Bytes[11:8] of the response

RSP3 offset = 0x3C

Field	Bits	Type	Default	Description
RSP3	31:0	R		Bytes[15:12] of the response

CLK_DIV offset = 0x40

Field	Bits	Type	Default	Description
VALID	8:8	RW		??
CLK_DIV	7:0	RW		Clock divisor

STATUS offset = 0x44

Field	Bits	Type	Default	Description
CMD_ERR_STATUS	21:16	R		Error status of commnd transfer:
				0x0: no error
				0x1: response timeout
				0x2: response wrong direction
				0x4: response BUSy timeout
ERROR	1:1	RWC		Indicate error in command or data
				0x0: no error
				0x1: error
EOT	0:0	RWC		Indicate the end of transfer (command or data)
				0x0: not ended
				0x1: ended