UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
421 of 1269
NXP Semiconductors
UM10503
Chapter 20: LPC43xx SD/MMC interface
20.6.4 SD Clock Source Register (CLKSRC)
20.6.5 Clock Enable Register (CLKENA)
20.6.6 Time-out Register (TMOUT)
Table 300. SD Clock Source Register (CLKSRC, address 0x4000 400C) bit description
Bit
Symbol
Description
Reset
value
1:0
CLK_SOURCE Clock divider source for SD card.
00 - Clock divider 0
01 - Clock divider 1
10 - Clock divider 2
11 - Clock divider 3
In MMC-Ver3.3-only controller, only one clock divider supported.
The cclk_out is always from clock divider 0, and this register is
not implemented.
0
31:1
-
Reserved
-
Table 301. Clock Enable Register (CLKENA, address 0x4000 4010) bit description
Bit
Symbol
Description
Reset
value
0
CCLK_ENABLE
Clock-enable control for SD card clock. One MMC card clock supported.
0 - Clock disabled
1 - Clock enabled
0
15:1
-
Reserved
-
16
CCLK_LOW_POWER
Low-power control for SD card clock. One MMC card clock supported.
0 - Non-low-power mode
1 - Low-power mode;
stop clock when card in IDLE (should be normally set to only MMC and SD
memory cards; for SDIO cards, if interrupts must be detected, clock should
not be stopped).
0
31:17
-
Reserved
-
Table 302. Time-out Register (TMOUT, address 0x4000 4014) bit description
Bit
Symbol
Description
Reset
value
7:0
RESPONSE_TIMEOUT
Response time-out value. Value is in number of card output clocks -
cclk_out.
0x40
31:8
DATA_TIMEOUT
Value for card Data Read time-out; same value also used for Data
Starvation by Host time-out. Value is in number of card output clocks -
cclk_out of selected card. Starvation by Host time-out. Value is in number
of card output clocks - cclk_out of selected card.
0xFFFFFF