Samsung S3C2451X User Manual page 475

S3C2451X RISC MICROPROCESSOR
CHANGE BUS WIDTH SEQUENCE
(1)
Disable Card Interrupt in Host
(3)
Mask Card Interrupt in Card
(4)
(5)
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.
START
(2)
SD Memory Only
Card ?
no
Change Bit Mode in Card
Change Bit Mode for Host
Figure 21-7Change Bus Width Sequence
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.
yes
(6)
SD Memory Only
(7)
Enable Card Interrupt in Card
(8)
Enable Card Interrupt in Host
HSMMC CONTROLLER
yes
Card ?
no
END
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