Samsung S3C6400X User Manual page 883

S3C6400X RISC MICROPROCESSOR
(5) Judge whether SD Bus voltage must be changed or not. If SD Bus voltage must be changed, go to step (6). If
SD Bus voltage does not to be changed, go to 'End'.
(6) Set SD Bus Power in the Power Control register to 0 for clearing this bit. The card requires voltage rising from
0 volt to detect it correctly. The Host Driver shall clear SD Bus Power before changing voltage by setting SD Bus
Voltage Select.
(7) Set SD Bus Voltage Select in the Power Control register.
(8) Set SD Bus Power in the Power Control register to 1.
Note: Step (2) and step (3) can be executed at same time. Also, step (7) and step (8) can be executed at same
time.
CHANGE BUS WIDTH SEQUENCE
(1)
Disable Card Interrupt in Host
(2)
(3)
Mask Card Interrupt in Card
(4)
Change Bit Mode in Card
(5)
Change Bit Mode for Host
The sequence for changing bit mode on SD Bus is shown in Figure 27-7.
(1) Set Card Interrupt Status Enable 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 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.
START
yes
SD Memory Only
Card ?
no
Figure 27-7. Change 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.
(6)
SD Memory Only
Card ?
(7) no
Enable Card Interrupt in Card
(8)
Enable Card Interrupt in Host
END
HSMMC CONTROLLER
yes
27-7