S3C2416X RISC MICROPROCESSOR
HSMMC CONTROLLER
20-41
5.15 CLOCK CONTROL REGISTER
At the initialization of the Host Controller, the Host Driver shall set the
SDCLK Frequency Select
according to the
Capabilities
register
.
Register
Address
R/W
Description
Reset Value
CLKCON0
0X4AC0002C
R/W
Command Register (Channel 0)
0x0
CLKCON1
0X4A80002C
R/W
Command Register (Channel 1)
0x0
Name
Bit
Description
Initial Value
SELFREQ [15:8]
SDCLK Frequency Select
This register is used to select the frequency of
SDCLK
pin. The
frequency is not programmed directly; rather this register holds the
divisor of the
Base Clock Frequency For SD Clock
in the
Capabilities
register. Only the following settings are allowed.
80h
base clock divided by 256
40h
base clock divided by 128
20h
base clock divided by 64
10h
base clock divided by 32
08h
base clock divided by 16
04h
base clock divided by 8
02h
base clock divided by 4
01h
base clock divided by 2
00h
base clock (10MHz-63MHz)
Setting 00h specifies the highest frequency of the SD Clock. When
setting multiple bits, the most significant bit is used as the divisor. But
multiple bits should not be set. The two default divider values can be
calculated by the frequency that is defined by the
Base Clock
Frequency For SD Clock
in the
Capabilities
register.
(1) 25MHz divider value
(2) 400kHz divider value
According to the SD Physical Specification Version 1.01 and the
SDIO Card Specification Version 1.0, maximum SD Clock frequency
is 25MHz, and shall never exceed this limit.
The frequency of SDCLK is set by the following formula:
Clock Frequency = (Base Clock) / divisor
Thus, choose the smallest possible divisor which results in a clock
frequency that is less than or equal to the target frequency.
For example, if the
Base Clock Frequency For SD Clock
in the
Capabilities
register has the value 33MHz, and the target frequency is
25MHz, then choosing the divisor value of 01h will yield 16.5MHz,
which is the nearest frequency less than or equal to the target.
Similarly, to approach a clock value of 400kHz, the divisor value of
40h yields the optimal clock value of 258kHz.
0
[7:4]
Reserved
Содержание S3C2416
Страница 33: ...S3C2416X RISC MICROPROCESSOR PRODUCT OVERVIEW 1 5 3 BLOCK DIAGRAM Figure 1 1 S3C2416X Block Diagram ...
Страница 38: ...PRODUCT OVERVIEW S3C2416X RISC MICROPROCESSOR 1 10 153 AIN 1 U14 195 EINT 10 GPG2 K15 237 SDATA 14 C18 ...
Страница 122: ...BUS MATRIX EBI S3C2416X RISC MICROPROCESSOR 3 4 NOTES ...
Страница 204: ...DMA CONTROLLER S3C2416X RISC MICROPROCESSOR 8 18 NOTES ...
Страница 284: ...WATCHDOG TIMER S3C2416X RISC MICROPROCESSOR 11 6 NOTES ...
Страница 320: ...REAL TIME CLOCK S3C2416X RISC MICROPROCESSOR 13 16 NOTES ...
Страница 344: ...UART S3C2416X RISC MICROPROCESSOR 14 24 NOTES ...
Страница 380: ...USB2 0 DEVICE S3C2416X RISC MICROPROCESSOR 16 34 NOTES ...
Страница 432: ...2D S3C2416X RISC MICROPROCESSOR 18 38 NOTES ...
Страница 446: ...HS_SPI CONTROLLER S3C2416X RISC MICROPROCESSOR 19 14 NOTES ...
Страница 455: ...S3C2416X RISC MICROPROCESSOR HSMMC CONTROLLER 20 9 4 9 SD COMMAND ISSUE SEQUENCE Figure 20 9 Timeout Setting Sequence ...
Страница 604: ...S3C2416X RISC MICROPROCESSOR S3C2416X RISC MICROPROCESSOR 23 22 NOTES ...
Страница 638: ...PCM AUDIO INTERFACE S3C2416X RISC MICROPROCESSOR 25 18 NOTES ...
Страница 653: ...S3C2416X RISC MICROPROCESSOR ELECTRICAL DATA 26 15 Figure 26 14 SDRAM READ WRITE Timing Trp 2 Trcd 2 Tcl 2 DW 16 bit ...
Страница 670: ...ELECTRICAL DATA S3C2416X RISC MICROPROCESSOR 26 32 NOTES ...
Страница 672: ...MECHANICAL DATA S3C2416X RISC MICROPROCESSOR 30 2 Figure 27 2 330 FBGA 1414 Package Dimension 2 Bottom View ...