Datasheet

582
SAM9X35 [DATASHEET]
11055E–ATARM–10-Mar-2014
All the timings for High Speed MultiMedia Card are defined in the High Speed MultiMedia Card System Specification.
The two bus modes (open drain and push/pull) needed to process all the operations are defined in the HSMCI Command
Register. The HSMCI_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 HSMCI_CMDR Control Register are described in Table
34-6 and Table 34-7.
Note: 1. bcr means broadcast command with response.
The HSMCI_ARGR contains the argument field of the command.
To send a command, the user must perform the following steps:
 Fill the argument register (HSMCI_ARGR) with the command argument.
 Set the command register (HSMCI_CMDR) (see Table 34-7).
The command is sent immediately after writing the command register.
While the card maintains a busy indication (at the end of a STOP_TRANSMISSION command CMD12, for example), a
new command shall not be sent. The NOTBUSY flag in the status register (HSMCI_SR) is asserted when the card
releases the busy indication.
If the command requires a response, it can be read in the HSMCI Response Register (HSMCI_RSPR). The response
size can be from 48 bits up to 136 bits depending on the command. The HSMCI embeds an error detection to prevent
any corrupted data during the transfer.
The following flowchart shows how to send a command to the card and read the response if needed. In this example, the
status register bits are polled but setting the appropriate bits in the Interrupt Enable Register (HSMCI_IER) allows using
an interrupt method.
Host Command N
ID
Cycles CID
CMD S T Content CRC E Z ****** Z S T Content Z Z Z
Table 34-6. ALL_SEND_CID Command Description
CMD Index Type Argument Resp Abbreviation Command
Description
CMD2 bcr
(1)
[31:0] stuff bits R2 ALL_SEND_CID
Asks all cards to send
their CID numbers on
the CMD line
Table 34-7. Fields and Values for HSMCI_CMDR Command Register
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)
IOSPCMD (SDIO special command) 0 (not a special command)