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UM10375
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© NXP B.V. 2011. All rights reserved.
User manual
Rev. 3 — 14 June 2011
21 of 368
NXP Semiconductors
UM10375
Chapter 3: LPC13xx System configuration
3.5.9 Internal resonant crystal control register
This register is used to trim the on-chip 12 MHz oscillator. The trim value is factory-preset
and written by the boot code on start-up.
8:5
FREQSEL
Select watchdog oscillator analog output frequency
(Fclkana).
0x00
0x1
0.5 MHz
0x2
0.8 MHz
0x3
1.1 MHz
0x4
1.4 MHz
0x5
1.6 MHz
0x6
1.8 MHz
0x7
2.0 MHz
0x8
2.2 MHz
0x9
2.4 MHz
0xA
2.6 MHz
0xB
2.7 MHz
0xC
2.9 MHz
0xD
3.1 MHz
0xE
3.2 MHz
0xF
3.4 MHz
31:9
-
-
Reserved
0x00
Table 15.
Watchdog oscillator control register (WDTOSCCTRL, address 0x4004 8024) bit
description
Bit
Symbol
Value
Description
Reset
value
Table 16.
Internal resonant crystal control register (IRCCTRL, address 0x4004 8028) bit
description
Bit
Symbol
Description
Reset value
7:0
TRIM
Trim value
0x1000 0000, then flash will reprogram
31:8
-
Reserved
0x00