Preliminary
S3C2451X RISC MICROPROCESSOR
HSMMC CONTROLLER
21-7
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
Specifications and information herein are subject to change without notice.
CHANGE BUS WIDTH SEQUENCE
Disable Card Interrupt in Host
(1)
START
SD Memory Only
Card ?
(2)
Mask Card Interrupt in Card
(3)
Change Bit Mode in Card
(4)
Change Bit Mode for Host
(5)
SD Memory Only
Card ?
(6)
Enable Card Interrupt in Card
(7)
Enable Card Interrupt in Host
(8)
yes
no
yes
no
END
Figure 21-7Change Bus Width Sequence
The sequence for changing bit mode on SD Bus is shown in Figure 21-7.
(1) Set Card Interrupt Status Enable(STACARDINT) in the Normal Interrupt Status Enable register to 0 for
masking incorrect interrupts that may occur while changing the bus width.
(2) In case of SD memory only card, go to step (4). In case of other card, go to step (3).
(3) Set “IENM” of the CCCR in a SDIO or SD combo card to 0 by CMD52.
(4) Change the bit mode for a SD card. Changing SD memory card bus width by ACMD6(Set bus width) and
changing SDIO card bus width by setting Bus Width of Bus Interface Control register in CCCR.
(5) In case of changing to 4-bit mode, set Data Transfer Width(WIDE4) in the Host Control register to 1. In another
case (1-bit mode), set this bit to 0.
(6) In case of SD memory only card, go to the ‘End’. In case of other card, go to step (7).
(7) Set “IENM” of the CCCR in a SDIO or SD combo card to 1 by CMD52.
(8) Set Card Interrupt Status Enable in the Normal Interrupt Status Enable register to 1.