User's Manual

Table Of Contents
S3C2450X RISC MICROPROCESSOR HSMMC CONTROLLER
21-7
4.6 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 21-7. Change 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.