Datasheet

917
SAM3X / SAM3A [DATASHEET]
Atmel-11057C-ATARM-SAM3X-SAM3A-Datasheet_23-Mar-15
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 37-6 and Table 37-7.
Note: 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 37-7).
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 37-6. ALL_SEND_CID Command Description
CMD Index Type Argument Resp 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 37-7. 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)