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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
25 of 571
NXP Semiconductors
UM10316
Chapter 3: LPC29xx Clock Generation Unit (CGU)
•
OSC1M (LP_OSC) – 1 MHz crystal oscillator
•
XO50M – up to 25 MHz oscillator
•
PL160M – PLL
•
FDIV0..6 – 7 Frequency Dividers
•
Output control
The following clock output branches are generated (
[1]
Maximum frequency that guarantees stable operation of the LPC29xx.
[2]
Fixed to low-power oscillator.
Table 11.
CGU0 base clocks
Number Name
Frequency
(MHz)
Description
0
BASE_SAFE_CLK
0.4
base safe clock (always on) for WDT
1
BASE_SYS_CLK
125
base system clock; ARM and AHB clock
2
BASE_PCR_CLK
0.4
base PCR subsystem clock; for power
control subsystem
3
BASE_IVNSS_CLK
125
base IVNSS subsystem clock for
networking subsystem (CAN, LIN, and
I2C)
4
BASE_MSCSS_CLK
125
base MSCSS subsystem clock for
modulation and sampling control
subsystem.
5
BASE_ICLK0_CLK
125
base internal clock 0, for CGU1
6
BASE_UART_CLK
125
base UART clock
7
BASE_SPI_CLK
50
base SPI clock
8
BASE_TMR_CLK
125
base timers clock
9
BASE_ADC_CLK
4.5
base ADCs clock
10
test clock; reserved
-
this is an internal clock used for testing
only. This clock is running at start-up and
should be disabled in the PMU for
power-down mode (see
for the
test shell clock configuration registers).
11
BASE_ICLK1_CLK
125
base internal clock 1, for CGU1