UM10503
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User manual
Rev. 1.3 — 6 July 2012
420 of 1269
NXP Semiconductors
UM10503
Chapter 20: LPC43xx SD/MMC interface
20.6.2 Power Enable Register (PWREN)
20.6.3 Clock Divider Register (CLKDIV)
Table 298. Power Enable Register (PWREN, address 0x4000 4004) bit description
Bit
Symbol
Description
Reset
value
0
POWER_ENABLE
Power on/off switch for card; once power is turned on,
software should wait for regulator/switch ramp-up time
before trying to initialize card.
0 - power off
1 - power on
Optional feature: port can be used as general-purpose
output on the SD_POW pin.
0
31:1
-
Reserved
-
Table 299. Clock Divider Register (CLKDIV, address 0x4000 4008) bit description
Bit
Symbol
Description
Reset
value
7:0
CLK_DIVIDER0
Clock divider-0 value. Clock division is 2*n. For example,
value of 0 means divide by 2*0 = 0 (no division, bypass),
value of 1 means divide by 2*1 = 2, value of ff means
divide by 2*255 = 510, and so on.
0
15:8
CLK_DIVIDER1
Clock divider-1 value. Clock division is 2*n. For example,
value of 0 means divide by 2*0 = 0 (no division, bypass),
value of 1 means divide by 2*1 = 2, value of ff means
divide by 2*255 = 510, and so on. In MMC-Ver3.3-only
mode, bits not implemented because only one clock divider
is supported.
0
23:16
CLK_DIVIDER2
Clock divider-2 value. Clock division is 2*n. For example,
value of 0 means divide by 2*0 = 0 (no division, bypass),
value of 1 means divide by 2*1 = 2, value of ff means
divide by 2*255 = 510, and so on. In MMC-Ver3.3-only
mode, bits not implemented because only one clock divider
is supported.
0
31:24
CLK_DIVIDER3
Clock divider-3 value. Clock division is 2*n. For example,
value of 0 means divide by 2*0 = 0 (no division, bypass), a
value of 1 means divide by 2*1 = 2, a value of ff means
divide by 2*255 = 510, and so on.
In MMC-Ver3.3-only mode, bits not implemented because
only one clock divider is supported. divide by 2*0 = 0 (no
division, bypass), value of 1 means divide by 2*1 = 2, value
of ff means divide by 2*255 = 510, and so on. In
MMC-Ver3.3-only mode, bits not implemented because
only one clock divider is supported.
0