UM10850
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© NXP B.V. 2016. All rights reserved.
User manual
Rev. 2.4 — 13 September 2016
27 of 464
4.1 Features
•
System and bus configuration.
•
Clock select and control.
•
PLL configuration
•
Reset control.
•
Wake-up control.
•
BOD configuration.
•
High-accuracy frequency measurement function for on-chip and off-chip clocks.
•
Uses a selection of on-chip clocks as reference clock.
•
Device ID register.
4.2 Basic configuration
Configure the SYSCON block as follows:
•
The SYSCON uses the CLKIN, and CLKOUT pins which can be configured through
IOCON. See
. RESET is a dedicated pin.
•
No clock configuration is needed. The clock to the SYSCON block is always enabled.
By default, the SYSCON block is clocked by the IRC.
•
Target and reference clocks for the frequency measurement function are selected in
the input mux block. See
.
4.2.1 Set up the PLL
The PLL creates a stable output clock at a higher frequency than the input clock. If a main
clock is needed with a frequency higher than the 12 MHz IRC clock, use the PLL to boost
the input frequency. The PLL can be set up by calling an API supplied by NXP
Semiconductors. Also see
Section 4.6.4 “PLL functional description”
and
.
4.2.2 Configure the main clock and system clock
The clock source for the registers and memories is derived from main clock. The main
clock can be selected from the sources listed in step 1 below.
The divided main clock is called the system clock and clocks the core, the memories, and
the peripherals (register interfaces and peripheral clocks).
1. Select the main clock. The following options are available:
–
IRC: 12 MHz internal oscillator (default)
–
CLKIN
–
Watchdog oscillator
–
The output of the system PLL
UM10850
Chapter 4: LPC5410x System configuration (SYSCON)
Rev. 2.4 — 13 September 2016
User manual