Samsung S5PC100 User Manual page 967

SD/MMC CONTROLLER
9.6 COMMAND REGISTER
Command Register
•
CMDREG0, R/W, Address = 0xED80_000E
•
CMDREG1, R/W, Address = 0xED90_000E
•
CMDREG2, R/W, Address = 0xEDA0_000E
This register contains the SD Command Argument.
The Host Driver checks 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 is responsible to write this register because the Host Controller does not protect the writing if
Command Inhibit (CMD) is set.
CMDREG Bit
Reserved [15:14] Reserved
CMDIDX [13:8]
CMDTYP [7:6]
8.12-32
Command Index
These bits are 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 are set to 00b for all other commands.
• Suspend Command
If the Suspend command succeeds, the Host Controller assumes that
the SD Bus has been released and it is possible to issue the next
command, which uses the DAT line. The Host Controller de-asserts
Read Wait for read transactions and stops checking busy for write
transactions. The interrupt cycle starts, in 4-bit mode. If the Suspend
command fails, the Host Controller maintains its current state, and the
Host Driver restarts 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 checks for busy before starting write transfers.
• Abort Command
If this command is set when executing a read transfer, the Host
Controller stops reads to the buffer. If this command is set while
executing a write transfer, the Host Controller stops driving the DAT line.
After issuing the Abort command, the Host Driver must 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
S5PC100 USER'S MANUAL (REV1.0)
Reset Value