Datasheet

SAM9261 [DATASHEET]
Atmel-6062O-ATARM-SAM9261-Datasheet_21-Jun-16
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There are different types of operations. Addressed operations always contain a command and a response token.
In addition, some operations have a data token; the others transfer their information directly within the command or
response structure. In this case, no data token is present in an operation. The bits on the DAT and the CMD lines
are transferred synchronous to the clock MCI Clock.
Two types of data transfer commands are defined:
 Sequential commands: These commands initiate a continuous data stream. They are terminated only when
a stop command follows on the CMD line. This mode reduces the command overhead to an absolute
minimum.
 Block-oriented commands: These commands send a data block succeeded by CRC bits.
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 MultiMedia Card operations.
34.8.1 Command - Response Operation
After reset, the MCI is disabled and becomes valid after setting the MCIEN bit in the Control Register (MCI_CR).
The PWSEN bit saves power by dividing the MCI clock by 2
PWSDIV
+ 1 when the bus is inactive.
The command and the response of the card are clocked out with the rising edge of the MCI Clock.
All the timings for MultiMedia Card are defined in the MultiMediaCard System Specification.
The two bus modes (open drain and push/pull) needed to process all the operations are defined in the MCI
Command Register (MCI_CMDR). 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 are described in Table 34-4 and
Table 34-5.
Note: bcr means broadcast command with response.
Host Command N
ID
Cycles Response High Impedance State
CMD S T Content CRC E Z ****** Z S T Content Z Z Z
Table 34-4. ALL_SEND_CID Command Description
CMD Index Type Argument Response Abbreviation Command Description
CMD2 bcr [31:0] stuff bits R2 ALL_SEND_CID Asks all cards to send their CID numbers on the CMD line
Table 34-5. Fields and Values for MCI_CMDR
Field Value
CMDNB (command number) 2 (CMD2)
RSPTYP (response type) 2 (R2: 136 bits response)
SPCMD (special command) 0 (not a special command)
OPCMD (open drain command) 1
MAXLAT (max latency for command to response) 0 (NID cycles ==> 5 cycles)
TRCMD (transfer command) 0 (No transfer)
TRDIR (transfer direction) X (available only in transfer command)
TRTYP (transfer type) X (available only in transfer command)