SH7721 datasheet(1102/1524 Pages) RENESAS

1102 / 1524 page

Section 31

MultiMediaCard Interface (MMCIF)

Rev. 3.00 Jan. 18, 2008 Page 1040 of 1458

REJ09B0033-0300

• RSPRD

Bit

Bit Name

Initial

Value

R/W

Description

7 to 5



All 0



Reserved

These bits are always read as 0. The write value should

always be 0.

4 to 0

RSPRD

All 0

R/W

These bits are cleared to H'00 by writing an arbitrary value.

Command response is stored.

31.3.8

Command Start Register (CMDSTRT)

CMDSTRT triggers the start of command transmission, representing the start of a command

sequence. The following operations should be completed before the command sequence starts.

Command transmission:

• Analysis of prior command response, clearing the command response register write if

necessary

• Analyze/transfer receive data of prior command if necessary

• Preparation of transmission data of the next command if necessary

• Setting of CMDTYR, RSPTYR, TBCR, and TBNCR

CMDR0 to CMDR4, CMDTYR, RSPTYR, TBCR, and TBNCR should not be changed until

command transmission has ended (the CWRE flag in CSTR has been set to 1).

• Setting of CMDR0 to CMDR4

The command sequences are controlled by the sequencers in each MMCIF side and MMC side.

Normally, these operate synchronously, however, these may become temporarily unsynchronized

when an error occurs or when a command is aborted. Take care to set the CMDOFF bit in OPCR,

to issue the CMD12 command, and to process an error in MMC mode. A new command sequence

should be started after confirming that the command sequences on both the MMCIF and MMC

sides have ended.

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