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UM10601
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2012. All rights reserved.
Preliminary user manual
Rev. 1.0 — 7 November 2012
13 of 313
4.1 How to read this chapter
The system configuration block is identical for all LPC800 parts. USART2 and SPI1 are
only available on parts
LPC812M101FDH20 and LPC812M101FDH16 and the corresponding
clocks, reset, and wake-up control bits are reserved for all other parts.
4.2 Features
•
Clock control
•
Reset control
•
Pin interrupt set-up
•
Configuration of reduced power modes
•
Wake-up control
•
BOD configuration
4.3 Basic configuration
Configure the SYSCON block as follows:
•
The SYSCON uses the CKIN, CLKOUT, RESET, and XTALIN/OUT pins. Configure
the pin functions through the switch matrix. See
•
No clock configuration is needed. The clock to the SYSCON block is always enabled.
By default, the SYSCON block is clocked by the IRC.
4.3.1 Set up the PLL
The PLL creates a stable output clock at a higher frequency than the input clock. If you
need a main clock with a frequency higher than the 12 MHz IRC clock, use the PLL to
boost the input frequency.
1. Power up the system PLL in the PDRUNCFG register.
Section 4.6.32 “Power configuration register”
2. Select the PLL input in the SYSPLLCLKSEL register. You have the following input
options:
–
IRC: 12 MHz internal oscillator.
–
System oscillator: External crystal oscillator using the XTALIN/XTALOUT pins.
–
External clock input CLKIN. Select this pin through the switch matrix.
Section 4.6.8 “System PLL clock source select register”
3. Update the PLL clock source<tbd> in the SYSPLLCKUEN register.
Section 4.6.9 “System PLL clock source update register”
4. Configure the PLL M and N dividers.
Section 4.6.3 “System PLL control register”
UM10601
Chapter 4: LPC800 System configuration (SYSCON)
Rev. 1.0 — 7 November 2012
Preliminary user manual