Atmel SAM4S-XPLD Atmel ATSAM4S-XPLD ATSAM4S-XPLD Fiche De Données

 815

SAM4S [DATASHEET]

11100E–ATARM–24-Jul-13

The two bits, RDPROOF and WRPROOF in the HSMCI Mode Register (HSMCI_MR) allow stopping the HSMCI Clock
during read or write access if the internal FIFO is full. This will guarantee data integrity, not bandwidth.

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:

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 

).

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.

CMD

S

T

Content

CRC

E

Z

******

Z

S

T

Content

Z

Z

Z

CMD2

[31:0] stuff bits

R2

ALL_SEND_CID

Asks all cards to send 
their CID numbers on 
the CMD line

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)