at91rm3400 ATMEL Corporation, at91rm3400 Datasheet - Page 377

• Manufacturer Part Number: at91rm3400
• Description: Atmel Advanced At91 Arm Microcontroller
• Manufacturer: ATMEL Corporation

Command-
response
Operation
1790A–ATARM–11/03
Both read and write operations allow either single or multiple block transmission. A multiple
block transmission is terminated when a stop command follows on the CMD line similarly to
the sequential read.
The MCI provides a set of registers to perform the entire range of MultiMediaCard operations.
After reset the MCI is disabled and becomes valid after setting the MCIEN bit in the MCI_CR
Control Register. The bit PWSEN allows saving power by dividing the MCI clock by 2 power
PWSDIV (MCI_MR) when the bus is inactive.
The command and the response of the card are clocked out with the rising edge of the MCCK.
All the timings for MultiMediaCard are defined in the MultiMediaCard System Specification
Version 2.2.
The two bus modes (open drain and push/pull) needed to process all the operations are
defined in the MCI command register. The MCI_CMDR allows a command to be carried out.
For example, to perform an ALL_SEND_CID command:
The command ALL_SEND_CID and the fields and values for the MCI_CMDR Control Register
are described in Table 66 and Table 67.
Table 66. ALL_SEND_CID command description
Table 67. Fields and Values for MCI_CMDR Command Register
The MCI_ARGR contains the argument field of the command.
To send a command, the user must perform the following steps:
•
•
The command is sent immediately after writing the command register. The status bit
CMDRDY in the status register (MCI_SR) is asserted until the command is completed. If the
CMD
CMD Index
CMD2
Field
CMDNB (command number)
RSPTYP (response type)
SPCMD (special command)
OPCMD (open drain command)
MAXLAT (max latency for command to response)
TRCMD (transfer command)
TRDIR (transfer direction)
TRTYP (transfer type)
Fill the argument register (MCI_ARGR) with the command argument.
Set the command register (MCI_CMDR) (see Table 67).
S
T
Type
bcr
Host Command
Content
Argument
[31:0] stuff bits
CRC
E
Resp
R2
Z
N
ID
******
Cycles
Value
2 (CMD2)
2 (R2: 136 bits response)
0 (not a special command)
1
0 (NID cycles ==> 5 cycles)
0 (No transfer)
X (available only in transfer command)
X (available only in transfer command)
Abbreviation
ALL_SEND_CID
Z
S
T
Content
CID or OCR
AT91RM3400
Command Description
Asks all cards to send their
CID numbers on the CMD
line
Z
Z
377
Z