Samsung S5PC100 User Manual page 942

S5PC100 USER'S MANUAL (REV1.0)
4.6 CHANGE BUS WIDTH SEQUENCE
The sequence to change bit mode on SD Bus is shown in Figure 8.12-7 and steps are described below:
(1) Set Card Interrupt Status Enable (STACARDINT) in the Normal Interrupt Status Enable register to 0 to mask
incorrect interrupts that may occur while changing the bus width.
(2) If SD memory card is used, 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. Set Bus Width of Bus Interface Control register in CCCR to change SD
memory card bus width by ACMD6(Set bus width) and SDIO card bus width.
(5) If you want to change to 4-bit mode, set Data Transfer Width(WIDE4) to 1 in the Host Control register. In
another case (1-bit mode), set this bit to 0.
(6) If SD memory card is used, 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 to 1 in the Normal Interrupt Status Enable register.
Figure 8.12-7 Change Bus Width Sequence
SD/MMC CONTROLLER
8.12-7