Command Register - Samsung S3C2416 User Manual

S3C2416X RISC MICROPROCESSOR

5.7 COMMAND REGISTER

This register contains the SD Command Argument.
Register Address
CMDREG0 0X4AC0000E
CMDREG1 0X4A80000E
The Host Driver shall check the Command Inhibit (DAT) bit and Command Inhibit (CMD) bit in the Present
State register before writing to this register. Writing to the upper byte of this register triggers SD command
generation. The Host Driver has the responsibility to write this register because the Host Controller does not
protect for writing when Command Inhibit (CMD) is set.
Name Bit
[15:14] Reserved
CMDIDX [13:8]
CMDTYP [7:6]
R/W
R/W Command Register (Channel 0)
R/W Command Register (Channel 1)
Command Index
These bits shall be set to the command number (CMD0-63, ACMD0-
63) that is specified in bits 45-40 of the Command-Format in the SD
Memory Card Physical Layer Specification and SDIO Card
Specification.
Command Type
There are three types of special commands: Suspend, Resume and
Abort.
These bits shall be set to 00b for all other commands.
Suspend Command
•
If the Suspend command succeeds, the Host Controller shall assume
the SD Bus has been released and that it is possible to issue the next
command which uses the DAT line. The Host Controller shall de-assert
Read Wait for read transactions and stop checking busy for write
transactions. The interrupt cycle shall start, in 4-bit mode. If the
Suspend command fails, the Host Controller shall maintain its current
state, and the Host Driver shall restart the transfer by setting Continue
Request in the Block Gap Control register.
Resume Command
•
The Host Driver re-starts the data transfer by restoring the registers in
the range of 000-00Dh. (Refer to Suspend and Resume mechanism)
The Host Controller shall check for busy before starting write transfers.
Abort Command
•
If this command is set when executing a read transfer, the Host
Controller shall stop reads to the buffer. If this command is set when
executing a write transfer, the Host Controller shall stop driving the
DAT line. After issuing the Abort command, the Host Driver should
issue a software reset. (Refer to Abort Transaction)
11b = Abort CMD12, CMD52 for writing "I/O Abort" in CCCR
10b = Resume CMD52 for writing "Function Select" in CCCR
01b = Suspend CMD52 for writing "Bus Suspend" in CCCR
00b = Normal Other commands
Description
Description
HSMMC CONTROLLER
Reset Value
0x0
0x0
Initial Value
20-25