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UM10503
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© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
165 of 1441
13.1 How to read this chapter
Ethernet, USB0, USB1, and LCD related clocks are not available on all packages. See
. The corresponding clock control registers are reserved.
The ADCHS is available on LPC4370/LPC43S70 parts only.
The Cortex-M0SUB subsystem core is enabled on parts LPC4370/LPC43S70 and
LPC436x/LPC43S6x, but the SGPIO and SPI peripherals are available on all
LPC43xx/LPC43Sxx parts.
13.2 Basic configuration
The CGU is configured as follows:
•
See
for clocking and power control.
•
Do not reset the CGU during normal operation.
•
For using core clock frequencies (BASE_M4_CLK) higher than 110 MHz with the
crystal oscillator, you must change the CGU configuration from the default setting in
several steps. See
13.2.1 Configuring the BASE_M4_CLK for high operating frequencies
To ramp up the clock frequency to an operating frequency above 110 MHz, configure the
core clock BASE_M4_CLK as described in
The recommended procedure to configure BASE_M4_CLK depends on the current clock
configuration of the part. There are two typical configurations:
1. After a power-up, reset, or when waking up from deep-power down mode. In these
situations, the boot code executes. After the boot process has completed, the clock
configuration of the part is as follows:
–
The core clock BASE_M4_CLK is connected to the output of PLL1 and running at
96 MHz.
–
The clock source for the PLL1 is the 12 MHz IRC.
2. After wake-up from Deep-sleep or power-down modes. In this case, BASE_M4_CLK
is connected to the IRC running at 12 MHz.
No special requirements exist for ramping down BASE_M4_CLK or changing any of the
peripheral base clocks either from low to high or from high to low frequencies.
UM10503
Chapter 13: LPC43xx/LPC43Sxx Clock Generation Unit (CGU)
Rev. 2.1 — 10 December 2015
User manual
Table 120. CGU clocking and power control
Base clock
Branch clock
Operating frequency
CGU
BASE_M4_CLK
CLK_M4_BUS
up to 204 MHz